I created a program with some lovely text boxes and buttons, but how do I get the inputted information from those text boxes and then add them together?
Ok. Use GetWindowText() to obtain the text from the 2 text boxes, and then use SetWindowText() to set the text in the 3rd text box. That simple if you know Windows programming.
I'll help you if you know enough to be able to create a GUI Sdk style Windows program with whatever development environment you are using. If you can't do that, there is no sense anyone here providing you with code you don't know how to compile. Like I said, I'd be happy to help, but you at least have to be able to accomplish that first step.