Block neighbors from using my internet?

i know this question is asked a LOT and i'm sorry, but i have a mac and all the directions i found were for windows users.

i bought the netgear router WPN824v3 and i'm using the connection right now.. i just want to set a password to block my neighbors from using it. nothing too complicated, just something an average user would have problems getting in to.

thank you in advance!
i know i need to password protect it, i mean how do i do it? sorry, should have clarified.