If you're shooting Video you have to set your camera to shoot at intervals... every camera is different, if it's a recent Canon, it might have that option.
If you're shooting film, you would have to set yourself up with your regular exposure, and shoot 1 frame every... whatever time you want... 1 minute, second, 2 mins... whatever you want the duration to be.
Just remember 24 frames = 1 second... so yea...
Time lapse would be really cruddy if you would have to do it by hand. But if you must, you must. The best way is to have an extended control which is not directly connected to the camera. If it is, every frame will move, and be different from one another... THUS it's better not to touch the camera...
What camera are you shooting with?
Maybe I can help you out better knowing then?