Step Carousel Image Issue

I am having an issue figuring out how to add images to specific posts within a step carousel. The slideshow does not grab the thumbnail of the post, I’m not actually sure how to add an image at all. The carousel was included in a downloaded theme and the site hosting the theme does not offer support. I can post the code for the slideshow if needed, the site I’m working on is http://www.theatomik.com.

I have also noticed while looking at the source of the carousel it’s looking for a <img src however I cannot find where to add a source.
-thanks