Access the page of the match you want to manage;

On the game's detail page, in the "Matchday" section, click the "Set Team" button;

On the page that appears, in the "General Information" section, you should choose the team captain. In the "Lineup Information" section, select the players you want to be starters "I", substitutes "B" or out of the squad "OC";

You can change the "Nr" (Number) and confirm the "Position" you want for each player in this game;

Finish by clicking the "Save" button.