@calchandoman: You are using Full Frame Free theme, which uses Featured Page Content. So, it will automatically take featured image of that page with image size of 400px by 225px. To change this in free version, you need to build child theme and edit the image size. But if you upgrade to pro version, you can use Featured Image Content instead of Featured Page Content, where you can upload image of your own choice and link to anywhere you like.
To reduce the space in left and right of featured content page, you can add the following css in “Appearance => Customize => Theme Options => Custom CSS Options” box:
@media screen and (min-width: 991px) {
#featured-content .hentry {
padding-left: 10px;
padding-right: 10px;
}
}