This movie will show you how to write a program to make your robot motors stop and go. It assumes that one motor is connected to pins 8 and 9, and the other one to pins 12 and 13.
If the motor goes backwards when you think it should be going fowards swap the two wires that go into the green connecting terminal.
To watch this video fullscreen click on the Youtube icon in the above picture and watch it on Youtube. It can go fullscreen there.