Help with Images In Catch Everest

I'm new to WordPress, and need some help with Catch Everest.  I like the theme, and I was able to set up menus, images, html stuff, but.... I can't figure out how to make the pictures of Mount Everest, etc. into the pictures I actually want!  My web address is www.classictheaterguild.com.  For right now, I switched to CatchBox, which doesn't have the Everest pictures at all, but I really preferred the Everest design with the sliding pictures.  I tried setting a Featured Image, but it didn't seem to do anything. Can anybody help?