From the Dashboard, select "Club Management" and then "Roster Builder".
Here you will select your "Event" and hit submit.
You will click and drag the hairpin icon next to the player's name to the team you would like to roster them on. A popup will appear allowing you to set a position or jersey number for the player if you choose to do so. Click "Add Player".
Note: All the players on the team currently have green check marks that signify the player has been approved.
You will now see that player on the team with a Yellow Triangle next to his name since he was just added and has not been approved yet.