Registering yourself

This is step one. Until you are registered in SA as a driver you can't do anything else.
You will need:
 - Form ANR, available here: Form ANR, second on the list
 - Two black-and-white passport-sized photos (there are usually shops nearby that will do these for you, costs around R15 to R20)
 - A large dose of patience

Fill out the ANR form, and take this with a copy of your passport (the one you mentioned in the ANR form) and your photos, and go to your local Traffic Dept office. Bear in mind that not all offices will provide this service, so check the list here (sorry Western Cape only!) before you go.
Be prepared to stand in the queue for an hour or more; bring some water, and maybe someone to trade places in the queue so you can sit down for a while - most of these centres have no air-con and can get very hot.
Good luck with step one!