Navigation Menu

Customization of navigation menu is easy. Code for navigation menu is given below
1.HTML Customize

<!– Main Menu Section –>
  <section class="menu">
    <nav class="navbar navigation">
      <div class="container">
        <div class="navbar-header">
          <h2 class="menu-title">Main Menu</h2>
          <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar"
            aria-expanded="false" aria-controls="navbar">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>

        </div>
        <!– / .navbar-header –>

          <!– Navbar Links –>
            <div id="navbar" class="navbar-collapse collapse text-center">
              <ul class="nav navbar-nav">

                <!– Home –>
                  <li class="dropdown ">
                    <a href="index.html">Home</a>
                  </li>
                  <!– / Home –>

                    <!– Elements –>
                      <li class="dropdown dropdown-slide">
                        <a href="#" class="dropdown-toggle" data-toggle="dropdown" data-hover="dropdown"
                          data-delay="350" role="button" aria-haspopup="true" aria-expanded="false">Shop <span
                            class="tf-ion-ios-arrow-down"></span></a>
                        <div class="dropdown-menu">
                          <div class="row">

                            <!– Basic –>
                              <div class="col-lg-6 col-md-6 mb-sm-3">
                                <ul>
                                  <li class="dropdown-header">Pages</li>
                                  <li role="separator" class="divider"></li>
                                  <li><a href="shop.html">Shop</a></li>
                                  <li><a href="checkout.html">Checkout</a></li>
                                  <li><a href="cart.html">Cart</a></li>
                                  <li><a href="pricing.html">Pricing</a></li>
                                  <li><a href="confirmation.html">Confirmation</a></li>

                                </ul>
                              </div>

                              <!– Layout –>
                                <div class="col-lg-6 col-md-6 mb-sm-3">
                                  <ul>
                                    <li class="dropdown-header">Layout</li>
                                    <li role="separator" class="divider"></li>
                                    <li><a href="product-single.html">Product Details</a></li>
                                    <li><a href="shop-sidebar.html">Shop With Sidebar</a></li>

                                  </ul>
                                </div>

                          </div>
                          <!– / .row –>
                        </div>
                        <!– / .dropdown-menu –>
                      </li>
                      <!– / Elements –>

                        <!– Pages –>
                          <li class="dropdown full-width dropdown-slide">
                            <a href="#" class="dropdown-toggle" data-toggle="dropdown" data-hover="dropdown"
                              data-delay="350" role="button" aria-haspopup="true" aria-expanded="false">Pages <span
                                class="tf-ion-ios-arrow-down"></span></a>
                            <div class="dropdown-menu">
                              <div class="row">

                                <!– Introduction –>
                                  <div class="col-sm-3 col-xs-12">
                                    <ul>
                                      <li class="dropdown-header">Introduction</li>
                                      <li role="separator" class="divider"></li>
                                      <li><a href="contact.html">Contact Us</a></li>
                                      <li><a href="about.html">About Us</a></li>
                                      <li><a href="404.html">404 Page</a></li>
                                      <li><a href="coming-soon.html">Coming Soon</a></li>
                                      <li><a href="faq.html">FAQ</a></li>
                                    </ul>
                                  </div>

                                  <!– Contact –>
                                    <div class="col-sm-3 col-xs-12">
                                      <ul>
                                        <li class="dropdown-header">Dashboard</li>
                                        <li role="separator" class="divider"></li>
                                        <li><a href="dashboard.html">User Interface</a></li>
                                        <li><a href="order.html">Orders</a></li>
                                        <li><a href="address.html">Address</a></li>
                                        <li><a href="profile-details.html">Profile Details</a></li>
                                      </ul>
                                    </div>

                                    <!– Utility –>
                                      <div class="col-sm-3 col-xs-12">
                                        <ul>
                                          <li class="dropdown-header">Utility</li>
                                          <li role="separator" class="divider"></li>
                                          <li><a href="login.html">Login Page</a></li>
                                          <li><a href="signin.html">Signin Page</a></li>
                                          <li><a href="forget-password.html">Forget Password</a></li>
                                        </ul>
                                      </div>

                                      <!– Mega Menu –>
                                        <div class="col-sm-3 col-xs-12">
                                          <a href="shop.html">
                                            <img class="img-responsive" src="images/shop/header-img.jpg"
                                              alt="menu image" />
                                          </a>
                                        </div>
                              </div>
                              <!– / .row –>
                            </div>
                            <!– / .dropdown-menu –>
                          </li>
                          <!– / Pages –>

                            <!– Blog –>
                              <li class="dropdown dropdown-slide">
                                <a href="#" class="dropdown-toggle" data-toggle="dropdown" data-hover="dropdown"
                                  data-delay="350" role="button" aria-haspopup="true" aria-expanded="false">Blog <span
                                    class="tf-ion-ios-arrow-down"></span></a>
                                <ul class="dropdown-menu">
                                  <li><a href="blog-left-sidebar.html">Blog Left Sidebar</a></li>
                                  <li><a href="blog-right-sidebar.html">Blog Right Sidebar</a></li>
                                  <li><a href="blog-full-width.html">Blog Full Width</a></li>
                                  <li><a href="blog-grid.html">Blog 2 Columns</a></li>
                                  <li><a href="blog-single.html">Blog Single</a></li>
                                </ul>
                              </li>
                              <!– / Blog –>

                                <!– Shop –>
                                  <li class="dropdown dropdown-slide">
                                    <a href="#" class="dropdown-toggle" data-toggle="dropdown" data-hover="dropdown"
                                      data-delay="350" role="button" aria-haspopup="true" aria-expanded="false">Elements
                                      <span class="tf-ion-ios-arrow-down"></span></a>
                                    <ul class="dropdown-menu">
                                      <li><a href="typography.html">Typography</a></li>
                                      <li><a href="buttons.html">Buttons</a></li>
                                      <li><a href="alerts.html">Alerts</a></li>
                                    </ul>
                                  </li>
                                  <!– / Blog –>
              </ul>
              <!– / .nav .navbar-nav –>

            </div>
            <!–/.navbar-collapse –>
      </div>
      <!– / .container –>
    </nav>
  </section>

You can add or replace the text for customizing the nav in li tag.
If you add new item on the navigation menu you have to add the page in href attribute for link that page.
Use dropdown class to for add dropdown menus & dropdown-fullwidth full width menu or mega menu. For more details visit bootstrap nav page – https://getbootstrap.com/docs/3.3/components/#navbar