Under the New User section there is a sticky post called Help For New Users.
Also, for chat, you haven't said how you're accessing the site. Laptop, phone, tablet? Android, Windows, Mac?
If you're in a laptop/pc there is a big paragraph at the top of the page telling you about how to enter chats.
If you're on an Android phone you have to go to the Play store and download it.
If you're on an iPhone you're out of luck for now.
Also, if you're on a phone I suggest scrolling to the bottom and clicking Full Site to use the forums. It's much easier.