How do i make friends with my boyfriend's friends?

I've hung out with them twice, and it's been awkward for me. They just act like i'm not there. They don't talk to me and i don't know what they're talking about, mostly, so i don't chime in. My boyfriend's nice and talks to me on the side, but i feel like i'm bringing him down because he has to "take care" of me because I can't just chill normally. Any suggestions to make these get togethers less awkward?