Overview
This will teach you how to play, I think?
Basics
Placing a Survivor:
Click on a empty green space (Only once, doing it twice will make your active survivor you clicked on run to it)
Click on the Recruitment Icon
Click a Survivor
Do this until you win
Also pick up any Supply-Drops that have landed for Gernades
???
Profit.
Extra Tips
Make you sure you get Tons of max Survivor Upgrades!
Throw gernades at Giant Zombies for max Damage
The first new survivor you should buy should be Trapper or Marine since the next few levels have Zombie Spawns away from the places you could use for Enforcers.