Why did he resign?

Caijguhf

Because your up a piece. And you have a better position. And mate is really easy too find. He proably saw mate on his side. And didn't want to take chances that you would find it.

Teja2chess; What?

Chessplayer your probly right

but was there a mate?

Hes up in material

Ah I was but my queen was very easly attacked

Resignation may have been a little premature, but black is quite lost. Persistent attacks on your queen would only weaken black's position - e.g. 7...d6 8. Qd4 Nf6 9. Bc4 c5 10. Qd3 and all black has to show for chasing the queen is a backward d-pawn and weak a2-g8 diagonal.

On the otherhand, being at ratings as low as yours (no offense), any play could happen. if i was black, i would at least ensure play and play to my very best. it could help improve my chess =) working on a losing game, helps your defense abilties perhaps?

There is no "easy mate" to find as someone earlier said. Meaning, there's no "mate in 2" or anything like that. However some players prefer to resign when they've blundered away a piece rather than to continue on hoping that you'll do the same. 

Black is quite lost due to being down a piece with ZERO to show for it (no compensation).  That said, when playing weaker players (like under 1400) there's no reason not to continue and see if an opportunity to get back in the game presents itself. 

He'll never tell. He is not a number. He is a free man.

thanks.

ah