Hello DCA Fan,
There are 2 routes you can take with this:
1. Register for an account selecting that you "already own this domain and will change the name servers on my own". By selecting this option you will be responsible for changing the nameserves on your domain through your registrar. You will receive the appropriate name servers in your welcome email.
2. Register for an account selecting that you "already own this domain and would like to transfer it to Sevaa". This comes will full domain technical support. We will change your name servers for you and assist you with any domain management. There is typically a $15 charge associated with this, but if you can hold off on your order for another week or so, its *very* possible that we'll be running a promotion that you'll be able to take advantage of
-Randy