Basic AI zombie

Hi i’m making my videogame and it’s my first project ever. It’s going pretty well but now i’m stuck with AI.

The game is a FPS zombie (something that reminds about Call of Duty zombie mode).
Where i can find a good tutorial just to start exploring basics AI ?
Thank you for your help.
P.B.

You could start by reading the Documentation on AI and Behavior Trees: https://docs.unrealengine.com/latest/INT/Gameplay/AI/index.html