This is a very good tutorial for mfc dialog based application beginers
http://www.codeproject.com/Articles/589/A-Beginners-Guide-to-Dialog-Based-Applications-Par
It's a 15 minute read and once you complete it i am sure you will be able to create a dialog with a button that executes some code. Also how to parse input from textboxes.
You could use your existing ascii drawing inside a textbox to create the feel of visual interaction, but if you want to use real images you will have to dig a little deeper by reading something like this:
http://www.codeproject.com/Articles/356/Bitmap-Basics-A-GDI-tutorial
Hope that helped.