These hands bother me.

***** Hand History for Game 2061100970 *****
$50 NL Hold'em - Monday, May 16, 23:49:03 EDT 2005
Table Table 36597 (Real Money)
Seat 5 is the button
Total number of players : 10
Seat 1: pkrzyn ( $46.95 )
Seat 7: Warrior2323 ( $134.2 )
Seat 9: The_Greek_1 ( $199.55 )
Seat 6: sejje ( $48.5 )
Seat 10: dales0045 ( $50 )
Seat 2: PreemPalver ( $38.25 )
Seat 3: njboy456 ( $45.44 )
Seat 8: yunsoonmp ( $49.6 )
Seat 5: WiCane ( $39.95 )
Seat 4: mth03d ( $76.6 )
sejje posts small blind [$0.25].
Warrior2323 posts big blind [$0.5].
** Dealing down cards **
Dealt to sejje [ As Ac ]
yunsoonmp folds.
The_Greek_1 calls [$0.5].
dales0045 folds.
pkrzyn folds.
PreemPalver folds.
njboy456 folds.
mth03d folds.
>You have options at Table 37425 Table!.
WiCane calls [$0.5].
sejje raises [$1.75].
Warrior2323 calls [$1.5].
The_Greek_1 calls [$1.5].
WiCane folds.
** Dealing Flop ** [ 6h, 4h, 9d ]
>You have options at Table 36586 Table!.
sejje bets [$6].
Warrior2323 folds.
The_Greek_1 calls [$6].
** Dealing Turn ** [ 5s ]
sejje bets [$12].
The_Greek_1 calls [$12].
** Dealing River ** [ 3d ]
sejje checks.
The_Greek_1 checks.
sejje shows [ As, Ac ] a pair of aces.
The_Greek_1 doesn't show [ 5d, Ah ] a pair of fives.
sejje wins $40.4 from the main pot with a pair of aces.

These kinds of hands I never understand what I should have done. Should I have bet out? I would have folded to much of a bet, and wrongly apparently.

They guy was playing pretty well. I just odn't understand.