You sign up with a username of course, that has nothing to do with your real-name, this is the only thing that is public. If, when requested for your personal information, you fill in false information, you are breaking the contract and facing legal action. The information is kept private, between you and NWR, and is only brought forth if legal issues arrive.
All sites have this same sort of disclaimer, dealing with copyright issues, or they we would be at legal risk themselves.
Not placing a whole song of your own wouldn't be sensible, and lowering the quality... Wouldn't that defeat the purpose of attempting to get your music heard?
W.