If you have already created the team,
- Click on the edit button for the Team
- This will open up the slide-out panel
- Go to the bottom of this panel, and you will see a field that says, players
- Select the players for the team
- Click save
If you haven't created a team,
- First, click on the 'Create a Team' button
- Fill in all the details for the team
- Then follow step 3 in the above list