Texas Hold'em (5 max)$0.25-$0.25 NL (real money),

Seat 2: P1 ($56 in chips)
Seat 3: villain ($36.45 in chips)
Seat 6: P2 ($4.50 in chips)
Seat 8: P3($4.75 in chips)
Seat 9: HERO ($36.15 in chips)

ANTES/BLINDS
P2 posts blind ($0.15), P3 posts blind ($0.25).

PRE-FLOP
HERO bets $0.75, P1 folds, villain bets $1.25, P2 folds, P3 calls $1, HERO bets $1, villain calls $0.50, P3 calls $0.50.

FLOP [board cards 5C,4H,2H ]
P3 checks, HERO bets $1, villain calls $1, P3 folds.

TURN [board cards 5C,4H,2H,7H ]
HERO checks, villain checks.

RIVER [board cards 5C,4H,2H,7H,9H ]
HERO bets $2, villain bets $5, HERO calls $3.

SHOWDOWN
villain shows [ QD,AH ]
HERO mucks cards [ AS,JH ]

I really had trouble playing that river - can anyone help?