First search gamesalad after you get there sign up free then download the thing for mac (it is just for mac not windows) then click on gamesalad after you downloaded it and installed it. Next click on start and find video then click on it and it will show you how to get started on making ipod touch games and just do what is shows you to do.

Here's what it looks like inside of gamesalad creater.

Oh, and if you publish it and people think its really cool then it will go to the app store and people will buy it.