By "party", I mean a physical social gathering of people for the purposes of having fun. It may be used in a sentence as "I am throwing a party!" or "Let's party!".
Basically what I am trying to say is the default "party".
I've never been to any, and I have no idea how people spend their time on parties, so I am curious how you did.
It can be fun to meet (new) people. I think, the key is to be sincerely interested in others and don't worry too much what they think about you.
If e.g. you are interested in programming or understanding how thinks work, it could be interesting to try to understand how other people tick. What motivates them, why etc. And if you get the impression that someone looks down on you, that's just another point of data about the world that person is living in. So the fun can stem from broadening your horizon (or from finding common ground).