Well, for first question, you post, play games and such. C: More on the question, here:
http://www.menewsha.com/forum/commun...ing-guide.html
As for second, you go to the Friends tab, enter someone's username and click the button "Add Friend". If/when they accept, they will appear on your friend list.
If you click the button "add contact" they will be visible in your friend tab, but not on your profile friend list and you won't send them a friend request.
And feel free to ask anything more. x3