What would you do in this situation......? (details inside)?

So I have this friend from my horseback riding. She's like 18 or 19 and I'm 16. We ride together and talk and stuff. So today I get this notification on Facebook. It says "______ has invited you to the event 'BONFIRE'" So I'm like ok....whatever. You know? So I click on it and check to see if I know anyone that's going. It looks like they're all/mostly people from her high school (she's in college) and no one that I know. I don't know what to do. Should I say yes? No? Maybe? What would you do in this situation?