Well, networking more or less just starts with talking with each other. Sometimes, it can do with comics, but others times, it can do with other topics that are interesting. It kinda has a bit to do with socializing and getting to know other people and how they approach the comic scene in their own way.
For my experience, I started with talking about the lore of my comic, but also being interested in what others are doing as well. Afterwards, we began to bounce ideas back and forth, offer each other some suggestions. Then, we started to gush over each other's characters or characters from franchises we liked together.
I won't say that networking ends with friendships all the time or that it will always help with promotion. But I can say that it helps with presenting yourself. There's no real requirement for this (other than not being an ass). Just offer what you can to other artists, express what you like and want to improve on your work, things like that.
I started doing this when I was on Deviantart, but I left that for these forums. Nowadays, I mostly interact with posts artists provide on Twitter and Tumblr. You don't have to dive in too deep either. Comments here and there help to build up 