Start by going to your Schedule:
Create a new activity and select Game:
Select Opponent:
Adding and Editing Opponents:
You can add or edit a new opponent by following the steps above. If you have already played the opponent once, they will be saved in your Opponent list for you to choose them if you meet again.
To delete an opponent from you list of saved opponenets, go to Team > Settings > Opponents. Press Opponent name > 3 buttons in the top right > delete opponent.