Changing a theme

I had a lovely friend build a framework for my site but I cannot grasp how to work my photos and writings into it. And I keep wanting changes. Can I select a regular WordPress template and switch it out with the one that is here http://tocatchamiracle.com ??

I picked my color and background image and I would like to be able to integrate that in with the new WordPress theme. Is it doable??

Thanks so much if anyone can help me, Denise