Pictures

I LOVE this theme. But, I can not figure out how to upload pictures into the featured image slide show on the front page. I have done everything I think makes sense, included uploading onto the lower right portion of my blog where it says “feature image”. Can someone please help! I don’t want to switch themes. HELP ??

oh and I should mention, one of the slides says “image to small” but this is the default text and not sure if it was there before. If it wasn’t what do I have to do?

My site is https://www.gottowantit.net and you can see what Im referring to.