My wife has been trying to cut/copy the theater pics to merge into one picture and cant figure it out. We set up the tripod and took pictures of the screen with the lights on and off and now we are stuck.
Any help on the program and function to use would be great!
I'd suggest posting this on a forum for the software you are going to use (likely based on budget or what you have on-hand that will work), whether it be Photoshop, GIMP, or something else. This is not theater-specific activity...most folks serious about photography have done this type of thing. If you do not get a good response here, you might on a photo editing site.
I know it can be done with the full version of Photoshop but I suspect you can do it with the simple edition (Photoshop essentials). Basic approach is to take two pictures on a tripod as you mention. In photoshop it is all about layers. So you take the one with the lights on and make that the first layer, then you take the one of the screen image and make that the second layer. You then select the eraser tool and erase the white screen on the first layer revealing the other shot. When you are done you merge layers and save the file. There are other methods where you would cut and paste the screen image.