Adding friends on your account is simple. All you have to do is follow these steps:
Click on your profile located on the left hand side of the page.
Then click on "Friends and Foes" right above your information.
Then you can start adding and accepting friends.
1. Find a user and send a friend request to him/her.
2. People you have sent a friend request to but they haven't accepted yet.
3. People who have sent you a friend request and you haven't accepted yet. Press the + button to accept and the - button to decline