We like to make this system as self service as it can be so if you would like to add another user on to the account, all you have to do is like on "My Account" and "User Administration" and Click "Add New User".
You will then be asked to add the relevant information about that user on to your account - it will even calculate the cost until your next payment date.
Please Note!
Those fields with the stars in are mandatory fields which means you have to fill those in to successfully set up another user.
Here are other relevant documents that may be of interest to you:-