you are reviewed for the first time. The reviewer will complete your profile page based on his visit. Once it is published by TER you will have an ID.

...You don't have an ID# until someone writes your first review. Tell your client to go to Reviews (tab at the top) click on submit a review. Read the info etc. He will fill out the form with your provider name and contact info, web site, ad, and so on. That will identify you. He may make a statement in the general details about you being a new provider and this is your first review. That helps TER keep from mixing you up with someone else. (Yes, it has happened.) Once his review is submitted, approved, and posted you will have a TER provider ID# and profile.

and give that username to the client.  

Make sure it's the correct spelling and all.  

Incorrect spellings usually causes headaches because you won't be able to find it under your username 'GoddessLolaV' and the client may not even remember what name (assuming he misspelled it) he put your review under.

Do it right the first time saves a lot of hassle for both parties and TER as well.

The Forest Waits