First you go to your Tools-drawer on your system partition and start RegTool.
Fill out the form and then you sends the request for a registration (requires network).
You'll recieve an verification email and you just follow the instruction in that mail to continue the key payment.
When you have payed for the key, you'll recieve a keyfile (normally very quickly) which you place on your system under DEVS:
That's it =)
