Xbox - How to Add An Friend To Your "Friends List" And Send Invite

Note:  When you are playing a Rival opponent on Xbox, your opponent's Xbox Gamertag will be placed temporarily into your Xbox's " Friends List" automatically. When your game has completed, your opponent's Gamertag will be removed automatically.  

(:16) In the case that your opponent’s Gamertag is not temporarily added into your Xbox’s “Friends List” you will have to manually add them.  To do so, press the glowing Xbox logo button on your controller. This will bring up the Xbox menu. Using the left stick move to the “People” tab. Move down to the “Find someone” box and press “A”.

(:35) The “Find someone” tab will then appear. Press "A" on the “Search or add players” box and type in the
Gamertag of your opponent. Once their profile has appeared on the right, move to it and press “A”.

(:49) Move to the "Add friend" box and Press “A” to bring up the different friend options. Here select “Friend” before moving to the Submit box and pressing“A”. 

Once you have submitted this request your opponent will receive a notification that you added them
as a friend.

Good Luck!