Still struggling with 10NL. Up and down, but a couple of these downs are serious.

I'm trying to learn my lesson from these big losses. Am I on the right track?

Party Poker No-Limit Hold'em, $BB (10 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

SB ($19.71)
BB ($8.95)
UTG ($19.71)
UTG+1 ($16.91)
UTG+2 ($10.55)
MP1 ($15.16)
MP2 ($4.45)
MP3 ($10.75)
CO ($13.13)
Hero ($12.35)

Preflop: Hero is Button with A, K. SB posts a blind of $0.05.
2 folds, UTG+2 calls $0.10, 1 fold, MP2 calls $0.10, 1 fold, CO calls $0.10, Hero raises to $0.6, 2 folds, UTG+2 calls $0.50, MP2 folds, CO calls $0.50.

Flop: ($2.05) 6, T, 4 (3 players)
UTG+2 checks, CO checks, Hero checks.

Should bet here, right? Last position, two overs, nut-flush draw? A good 50% of pot doesn't disuade the draw hands necessarily, but should get PP that didn't hit out and overcards?

Turn: ($2.05) 9 (3 players)
UTG+2 checks, CO bets $0.75, Hero calls $0.75, UTG+2 folds.

CO is a bit of a loose-passive player. But I had real trouble putting them on a hand. Probably would guess TPWK or something.

River: ($3.55) 9 (2 players)
CO bets $3, Hero raises to $6, CO calls $8.78 (All-In), Hero calls $5 (All-In).

Right. Donkish play here. The a-flush is not the nuts on a paired board. Should have just called the original bet. Or do I fold here?

Final Pot: $26.33

Results in white below:
CO has 9c 9d (four of a kind, nines).
Hero has As Ks (flush, ace high).
Outcome: CO wins $26.32.

Second hand was in many ways worse. (How could that be? I hear you cry).

Party Poker No-Limit Hold'em, $ BB (10 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

MP3 ($10.55)
CO ($10.30)
Button ($2.35)
SB ($8.63)
BB ($10.10)
UTG ($14.75)
UTG+1 ($9.65)
UTG+2 ($1.35)
MP1 ($14.49)
Hero ($14.87)

Preflop: Hero is MP2 with A, A. CO posts a blind of $0.15. SB posts a blind of $0.05. MP1 posts a blind of $0.15.
3 folds, MP1 (poster) checks, Hero raises to $0.3, MP3 calls $0.30, 1 fold, Button calls $0.30, SB (poster) calls $0.25, 1 fold, MP1 folds.

Too many seeing this flop, unusually bold for this table.

Flop: ($1.60) Q, T, K (4 players)
SB bets $1.01, Hero calls $1.01, MP3 calls $1.01, Button calls $1.01.

Horrible, horrible flop. Raise here? Find out if I'm up against a made hand? SB is tight-passive should listen here.

Turn: ($5.64) 2 (4 players)
SB calls $7.32 (All-In), Hero calls $7.32, MP3 folds, Button calls $1.04 (All-In).

Donk call, right?

River: ($21.32) 6 (3 players, 2 all-in)

Final Pot: $21.32

Results in white below:
SB has Jh As (straight, ace high).
Hero has Ah Ac (one pair, aces).
Button has 4s Jd (high card, king).
Outcome: SB wins $21.32.