From the main screen, click on Campaign Editor, and then another screen will open up outside of Starcraft. This is the Campaign Editor. The Campaign Editor lets you make your own custom map. The Campaign Editor has a lot of stuff you can make/do, but I'm not going to go into that. It is very easy to just experiment with it and learn what all the buttons/features do. What I will encourage you to do though is to make a map. It probably will take some time, but the ending result is the pride that you made a map. Once you made a map you can play it against some computers on Singler Player, Custom Maps...Or you can play it with friends online on Battle.net. Anyway you play it, you still will have fun. I think that the Campaign Editor feature of Starcraft is a brilliant and useful feature