Navigate to the match channel you want to submit your lineup for.
Click Select lineups.
You can use the search bar in the lineup menu to easily search for teammates or scroll through the members list to select your lineup. Once your lineup has been chosen, the teammates you selected will appear under the Your roster column. Click Submit lineups.
Note: If you want to choose a member that is not currently part of your server, you must add them to your server first in order to submit them in your match lineup.