Betting odds, how does it work and where to bet?

I'm thinking of putting a bit of coin on Holm tonight. Can I still bet, and if so, where? I kind of get how odds work, but I'd like to hear the payout if I put $100 on Holm, given the current odds.

Last I saw, Holm was +255. That means you'd bet $100 to win $255. Cybord is -310 meaning you'd risk $310 to win $100.

Most online sportsbooks will let you bet right up until the fight starts.

As far as where to bet, I don't have any recommendations.