Invalid Player i like to have sex scam

http://imgur.com/6qtVx
proof of trade
He told me he would send me a key through gift wrap if I traded my Strange Sniper Rifle in tf2. Never got the key. He changed his name immediately after the trade. Also played under Emo Freak

Invalid format. Please use the format found in this thread.

Assuming he meant a Mann Co Supply Crate Key, you should have traded the Rifle for the Key in the same window, since they are both tradeable.
However, as Canadian said above, you need to follow the appropriate report format.