need help with pics and gimp

[bodiscool]

iv just finished a sculpt of a vampire bust.took some pics (not great!) and ive been trying to adjust using gimp with not much luck ive read the artical on here but im at a loss.wen i adjusted the levals it was very dark and made the pic worse play around manualy but had no joy.so started again this time leaving the levals as they were.i then croped the pic then scaled it.i scaled the width to 600 then clicked the chain but the height was 1340.so i played around with it all but all i managed to do was realy mess everything up any help or advice would be greatly apprecated