How does it work here?

Like the title, I really want to ask how everything works here.

Hello everyone. I am a new member here, just created this account for 4 days.

So far, I am trying to complete my profile here, I try to fill out everything I can. If you look at my profile, you can see I wrote a lot. However, 4 days past, and I can't think of anything new to add to my profile.

So I decided to move to the next part: make contacts with people here. I want to ask how would you guys make new friends here? Just send message to them? Is it intrusive? I know, if I worry about that, what's the point of creating an account here? But still, ...

Another thing I am trying to do now is look at the forum, see if there is anything I find interesting, then reply it. Well, I only do it once so far, but more to come in the future. I have been here for only 4 days, what do you expect?

Looking forward to your replies.