Okay guys, this lesson cost me $25 so please help me learn it.

How might I have played this differently or did I even play it wrong?

Ultimate Bet No-Limit Hold'em, $.25 BB (10 handed)

Hero ($24.85)
UTG ($2)
UTG+1 ($18.50)
UTG+2 ($22.15)
MP1 ($26.55)
MP2 ($7.10)
MP3 ($29.15)
CO ($23.30)
Button ($44.95)
SB ($6.25)

Preflop: Hero is BB with , .
UTG+1 calls $0.25, 3 folds, MP3 calls $0.25, 2 folds, SB completes, Hero checks.

Flop: ($1) , , (5 players)
SB checks, Hero bets $0.5, UTG calls $0.50, UTG+1 calls $0.50, MP3 raises to $1.5, SB folds, Hero raises to $5.5, UTG calls $1.25 (All-In), UTG+1 bets $18.25 (All-In), MP3 calls $18.25, Hero re-raises (all-in)$24.60, MP3 calls.

Turn: ($67.45) (4 players, 3 all-in)

River: ($67.45) (4 players, 3 all-in)

Final Pot: $67.45

Results in white below:
Hero has 6d 7d (straight, nine high).
UTG has Jd Td (one pair, nines).
UTG+1 has 6h 7c (straight, nine high).
MP3 has 9h 9s (four of a kind, nines).
Outcome: MP3 wins $67.45.

You got all the money in as a big favorite. Can't improve on that. Just bad luck

I'm not sure I understand the question. You flopped the stone cold nuts and were able to get all your money in on the flop. You've gotta like that, of course, the more and more people that are in, the more I'm getting that feeling that this is one of the times that poker is going to screw me over with some ridiculous crap, but hey, this is Hold Em, what are you gonna do, fold your nuts on the flop? Wait for a safe turn card? It's not Omaha, get that money in there, live with the consequences.

got 10 outtered, nothin you can do there
its already been said, but ive herd it so often, it feels good to say it
you got you're money in with the best hand, nothin else you can do, thats poker

When I posted this last night I was thinking there was something I should have seen with all of the action. JJ, I was wondering just that. I'm not going to fold on the flop, of course, but would it have been better to just call and save those last chips? But I would have been all-in on the turn anyway and the set wouldn't have folded. So pushing was the play.

Stoneburg, oddly enough I had 5 outs to hit the flush and take the two side pots, which was the largest part of this pot. Now wouldn't that have been a wierd ending to this hand?

Anytime that I get someone all in on the flop whilst I hold the nuts I am very happy. What more do you want? If you do this often enough you won't go broke.

Agree with the A Train. But Stoneburg is also right. If everybody flipped over their cards you'd have to do some serious calculations to find out whether a fold might not be the best play. Craziness.