Can I use post formats with Gateway?

Hello,

I am using the Gateway theme and I would like to know if it would be possible to use post formats to customize my blog posts. I want to make the featured image a banner that spreads horizontally across the top of the screen, and I would like it to replace the page header, which is the header for the home page of the site.

My site is Storiesofgeorgia.com. When I first downloaded gateway three weeks ago it had a post format option. However it suddenly disappeared. Is there any way to add this customization to the theme?

Once again, to clarify- the home page header image currently appears on all blog posts. I would like to replace this home page header on the blog posts with the featured image of the blog, so that it shows up horizontally across the blog post.

Thank you for your time!