How many mistakes did I make with this set?

[spex x]

I played this hand the other day in a 2/5 NL live game. How many mistakes did I make? Should I have led out on the flop? Should I have check-called the turn? Check-folded? What do I do on the river? I had $500 in chips and the button had about $400.

It was my very first hand at the table and I posted the $5 from MP. I didn't know any of the other players at the table, no reads at all. No action to me, I had Q[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/heart.gif[/img]. I checked. The button limped as did the blinds ($20 pot). The flop came Q[img]/images/graemlins/club.gif[/img] Q[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/spade.gif[/img]. SB and BB checked to me, and I checked. The button bet $15, blinds folded, and I raised to $50. The button called ($120 pot). The turn was 8[img]/images/graemlins/club.gif[/img], I bet $50, got called ($220 pot). The river was a 9[img]/images/graemlins/club.gif[/img]. I checked and the button moved in for $200. What do I do?