have players in selection view and you see status bars of morale and condition. Morale is the one on the left. When it's low you click it and if on browser then click how many blue pack & confirm, on phone it will bring you to player card Injury/Morale/Condition page and you can select how many of your boosters to spend. You should only every need to use 2 blues (in singles they are 10% but two magically seems to make them happy), no matter how bummed they are. The reds the most you need to ever spend no matter how much longer the injury days is 5, and the greens boost 15% condition.