Hi there,
importing a Site on a pre-build website is not advisable, as it ill import content, plugins, new menus etc…. especially just to a Page Hero.
To create your Page Hero.
1. Go to Appearance > GeneratePress and activate the Elements module.
2. Appearance > Elements – Add New > Select Header element.
3. In the Content area provided add your markup eg.
<h1>My Big Title</h1>
If you want to use the content title to display dynamically for each page the hero exists on the add this instead:
<h1>{{post_title}}</h1>
4. Edit the top and bottom padding to give the hero some height. Eg. 200px Top and 200px Bottom
5. Select the Background Image option. You can either use a Custom Image, and select one directly within the Header Element, this will be used on all pages with the hero. Or select Featured Image and this will display the featured image that has been assigned to any page or post.
6. On the Display Rules Tab > Location – select the areas you wish to display the Header Element. e.g:
Entire Site – everywhere
Front Page – is just your home page
Pages > All pages – just your pages
etc.
In addition to the Header Element documents here are some examples:
https://docs.generatepress.com/article/page-hero-examples/