I was wandering if there is a law on how many bullets you can legally have in a handgun, and where on the web these facts would be posted

First, they are technically called cartridges, the bullets are what come out the barrel. Magazine cap. varies from state to state. Kalif. is one. There is probably info. on the NRA website.

Some areas require a "Clinton" magazine which is limited to 10 rounds. Where there are no limitations some pistols have a magazine capacity of 17 or 18 rounds.