How would I make a friend list system?

[aPaperWeight]

Question
How would I make a friend list system?

What do I want in this?
Be able send someone a friend request
Be able accept friend request
View your friends on a list
Be able to view your friends profile and stats

Extra
Please either send tutorials to help or write your own tutorial in the comments! This will help a lot and will include proper credit.

[aPaperWeight]

Here is a screenshot of a mock up of the friend list in game.