There are two ways you can register, one way is if your employer is registered on e filing they can register you for personal income tax on their e filing profile.
Alternatively you can do a manual application, In order for you to register for tax you need to to submit the following documents to SARS in person
Certified copy of your ID document
Letter from the bank to confirm your bank account
Proof of residence
ABOUT PERSONAL TAX
Once you start working you will need to submit a personal tax return to SARS once per year, either via e filing or alternatively you can file your tax return at a SARS branch in person. The form used to file this return is called an ITR12 and is available on your e filing profile.