CodeWarrior puts a placeholder file. It is probably "hello.c", "hello.cpp", "sillyballs.c", or something like that. You must either put your code in this file or when in your Project Window, drag it to the trash. It won't put anything in the Trash, just delete it from the project. There also may be other placeholder files, such as resource files, which can be deleted.
I'm just a novice programmer, and am relying from memory, so the advice of the previous post is really the best, but this may help to get you started. You might find that CodeWarrior is putting files in unexpected places (depending on which environment you are using) if you do not specify in the Project Manager preferences ...