Go to your index file and change the content of the banner.

<section class="slider">
	<div class="container">
		<div class="row justify-content-center">
			<div class="col-lg-9 col-md-12">
				<div class="text-center">
					<span class="d-block mb-3 text-uppercase">Prepare for new future</span>
					<h1 class="animated fadeInUp mb-5 text-white">Helping customers be their best in the moments that matter.</h1>
					<a href="#" target="_blank" class="btn btn-main animated fadeInUp mr-1 mb-2 mb-lg-0" >Get started<i class="btn-icon fa fa-angle-right ml-2"></i></a>
					<a href="#" target="_blank" class="btn btn-solid-border animated fadeInUp" >Discover Sulfur</a>

 2. Image Change from CSS

 background: url(“../images/bg/banner-2.jpg”) no-repeat;