help with this opening


It is called the Center Game (ECO code C21). You can look at a database with some games using this opening here: http://www.chessgames.com/perl/chessopening?eco=C21
You can also download that website's complete database of games with this opening (only 327 total games) if you're interested in studying it further.
1.e4 e5 2.d4 is the Center Game; 2...exd4 3.c3 makes it the Danish Gambit, I believe (though I really should look this stuff up instead of shooting from the hip).
Edit: yes, I was right: http://en.wikipedia.org/wiki/Danish_Gambit

It is all the Center Game. The Wikipedia entry says "The Danish Gambit is a variation of the Center Game that is important enough to be treated on its own. It is C21 in the ECO classification." According to ECO's own website, though, C21 refers only to:
1. e4 e5 2. d4
- without 2... ed4
- 2... ed4 without 3. Qd4
Doesn't say anything about the so-called Danish Gambit uniquely. Any third move by White other than 3. Qd4 is C21, and the variation with 3. Qd4 is C22. So much for "treated on its own."

The Danish is particularly scary especially if played that far, kinda "doubly accepted". Usually black chickens and does not play 4...cxb2 returning his c pawn and settling for a single pawn advantage. Of course, such is a matter of style and open to debate. It is still the Danish as long as 2...exd4 3 c3 is played as mentioned above.

I play it as white. Just try not to panic. I would accept the pawn. Keep your hands off the queen. Develop your pieces. Castle. Try playing it as white :-) Honestly, there's no better way to develop empathy. Remember, if you play accurately as black, you will find yourself up two pawns in the endgame. Remember, all gambits are probably funamentally unsound.

Its called the dannish gambit i should know i had an old chess book show me it. if black didnt play c3 on the 3rd move then thats the center game....