When you start the game go into the Ultimate team (UT) menu, if this is your first time on ultimate team you will have a few tutorials to go through but you will get to the same place. When your in the UT menu flick along to single player then select squad builder challenges. Choose the lets get started challenge then the first exchange. From here just place a goalkeeper into your team, it can be any goal keep then submit that team and your achievement will pop!