Hover over Competitions and select Team Setup.
Find your team and click Manage Members.
A list of members will appear on the left.
You can filter the list using any of the available filters.
Click the green arrow next to the player you want to add to your team. This will move their name to the right side.
You can select a player number and position. These are optional.
If you select the wrong player, you can remove them from the team by clicking the red arrow before their name.
When you have added all your team members, click Save.