Page Banner and Text

I recently started working on a wordpress site that has a customized theme utilizing featured images and banners. I can’t for the life of my find where I can add and edit the banner on a specific page. In looking at a page that is already developed I find this text referencing the banner but can’t figure out how to add it to a new page, Any suggestions would be greatly appreciated!

<section id=”banner”>
<img width=”815″ height=”350″ src=”https://www.corionlandscape.com/wp-content/uploads/2012/02/truck.jpg&#8221; class=”attachment-large wp-post-image” alt=”truck” title=”truck” />
“<section id=”banner-text”>
<h1>Corion’s Services for Your Business</h1>
</section>