what i doing to make site good?
uhm... it is a very complex question to be answered in a post
but! you can read the gambling section here and see how some of the gambling sites should look like
you may wanna visit this topic of HHampuz and look at the top gambling sites:
https://bitcointalk.org/index.php?topic=4832500.0your site does look like a school project, to be honest and I'm sure the bankroll for it is between 0.001-0.05 bitcoins
well, the first thing to look at- fairness, gamblers must be sure the rolls are not manipulated
then the proof of funds-prove that you can pay the winners if they are lucky enough to win
not even talking about smaller things like interface,FAQ,proper promotion etc. etc.