You can manage your friends and blocked lists on "Community" in the game menu or pressing V.
To add someone as a friend, type their name on the field in the friends list making sure you are typing their name correctly and click on "Add Friend".
Another possible way in case you are next to the player you want to add is to right click on them and click on "Add Friend".
The other player needs to be online to receive and accept your request.
You can manage your friends and blocked lists on "Community" in the game menu.
To add someone as a friend, type their name on the field in the friends list making sure you are typing their name correctly and click on "Add Friend".
Another possible way in case you are next to the player you want to add is to go on Community > Nearby Players > select your friend's character > Add Friend.
The other player needs to be online to receive and accept your request.