There's a boy I want to talk to really bad (I'm a bisexual male) but I don't know how or what to talk about.... what should I do?

Just try and find something you have in common, talking is easy when it's about something you like. I know it's hard to get the words out sometimes, but once you break the silence you'll find that they'll be easier to talk to than you think. Just remember, he's a person that has things he likes and dislikes, once you get to know him the conversation will flow naturally.