I went to Disney & they had a booth you could get ur picture taken w/ ur head & the body of a star w

and I mean just how do I set up the application to do all this in my own. not merely by means of photoshop. I want to copy this booth with a comicon convention to make several cash :D I understand how to display my personal computer on a tv (easy) but what software do I use to adopt pictures utilizing premade templates I create myself?