How to do a NRTP rating?

Hi Everyone,

I'm just became a USTA member in order to sign up to play a few tournaments while I'm in town. I've been playing for 15 years casually with friends but now I want to formally compete but I have no idea my rating. Can anyone recommend how I go about doing this? Is it through a USTA member or just by playing with a certificated rated USTA member? Any help is appreciated. Thanks.