How do I make a motor that will reverse?

[Husafan]

I am sorry to be posting here since everyone seems so knowledgable, but I have absolutely no expereince in electronics. Basically, I want to be able to make an electric motor go forward on a 3' track, and when it gets to one end, reverse, and so on, so that it goes back and forth on this track. I don't need speed control or anything like that, and it seems like this should be a pretty simple circuit from I what I do know. If anyone could give me any help on this, it would be greatly appreciated.

Thank you in advance,
Joshua
husafan@f2s.com