nice to meet u all bros today, i need some help on my pics, my kuning shots below

also is there anywhere hoe to learn to adjust curve in PS? I totally duno how to use it, instead all my overexposed shots i duplicate layer and (multiply) only.
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also u all know i boug the battery haul ya, anyway its working great so far, tested with my fren duno thinga-magic volt tester, he said the voltage output is quite consistent, so should be good for high end equipments which needs consistent power( if i know wat he is talking about) anyway saw in the brochure, with every purchase of battery, ur entitled to enter a contest and win!! my shots of this girl very

wanna see which bro wanna try their luck submitting their pic..pm me so i can give u the receipt number as proof of purchase....
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must be this girl
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just a question,
I need to know where I go wrong...
1. How do i get clean clear correct white balance like sidewinderz pics? I am using flash (auto) 1/80 ISO1600 F5.6(variable and the smallest my lens can do)
2. How to get clear background (without model's shadow) when using with flash?