Off topic but how do you private message someone and how do you start a forum or discussion?
To talk to someone privately (instead of posting on threads), you can use "PM" (PM = "personal message", bit like email)
You need to make at least 5 posts and be active for at least 24 hours to get access.
If you don't know what to post, post in some of the "games" threads (see "offtopic" section).
Once you have PM access, when you hover the mouse pointer over a user name, you'll see a "start conversation" button...
To start a discussion, look for the big red "POST THREAD" button (top right), from the main page, or from one of the sub-sections.