In the event one of your players gets booked you'll need to add it to the match timeline.
Select the Matchday tab then Match Stats and you can then select whether it was a yellow card, a red card or a player was sin binned.
When you've selected the level of caution you will be shown a list of your players, so you can select which player was booked.
Once you've selected the player it will appear in the live match timeline.