You have 20 troop who have 20 ammo and 20 health.
Click on your troop then click in the location you want to move them to move the troop.
Protect the commander in the middle .
Ammo pads are in the top left and right corner and give you ammo.
The healing pad is beside the commander it will heal your troops
The power up pad it beside the commander as well the more troops you put on it the faster it charges if it gets fully charged it kills all the zombies
Good luck.