The buddy list is a small and simple feature to stay in touch with your friends in goalunited. You find it on the right side of your screen. Once a manager is on your buddy list, or if you became a fan, you can open his contact page right through the buddy list tool.
Here you see all of your buddies, a list of all of your buddy list requests (both, sent by you and sent by others to you), your ignore list, and a list of the managers you are a fan of.
To become buddies with another manager you have to send him a request. Go to his contact page and hit the "request" button on the left side. Once the manager accepts the request, he moves into your buddy list.
If you receive a request, simply open your buddy list and open the request tab. You will then be able to accept or deny it.
Being a fan
You can also become fan of another manager. The other manager does not have to accept a request, so this is a good way to keep track of a team you came across in a tournament or your league, or maybe a first league team you find interesting.
To become fan of a team also use the contact page and hit the "become a fan" button on the left. As soon as you become a fan the manager shows up in the fan tab in your buddy list and is easily selectable.