I downloaded a c++ program from the net. it came as a zip file. I extracted it and opened it with a visual studio but i don't know which is the main form. I tried to execute the forms one after the other. one of them debugs and when i click on start debugging an empty form like notepad opens. also i have seen a file with the extension.cg but i don't know what i should use to open that one. I am using visual studio 2012.