I assume you've downloaded the client from folding.stanford.edu? If so (or if you didn't, do so, then) put in whatever username you want (though I'd recommend folding as your EVGA name for ease of obtaining your EVGA Bucks down the line) and team number 111065 (that's EVGA's number). I'd also strongly recommend getting a passkey
here and copying it over to the appropriate field so you don't make any typos. Without a passkey you won't get bonus points, and they make up the large majority of points earned on pretty much any semi-recent hardware. The point levels required to get Bucks basically require you to be getting bonuses.
Note that you won't see any bonus points until after you've turned in 10 WUs with the passkey.