do events happen here?

Indeed. You can check the Holiday Schedule for a list of regular events but there can be unique other events as well like Quest-A-Thons for example.

thanks,also where is the list of people online?

You can see how many people are online by viewing the dashboard on the left side, where it has your username and sP amount and all it says "Users Online: ###"

As far as I know, there is no list of every user who is currently online. You can sometimes see when people are online on their profile if they have the section that says when they were last seen, but some people may have that feature turned off anyway. There is something in the preferences that's Stealth Mode that lets you hide when you are online.

Is there a place to chat?

well, there are the forums where you can find all sorts of topics that might interest you. there's also the shoutbox, which functions as a live chat. the shoutbox widget can be added to your sidebar on this page, but it's disabled in the sidebar during holidays – we're currently in the middle of our easter event, Vesnali – so for now you'll have to use the full page version i linked.

be sure to read through the forum rules and shoutbox rules first, though.