Yo, I have been using wireless inter internet for awhile, and Ive been very concerned of people using it as of right now there is no security code.

The thing is I want to put a code but I dont know how, I have contacted my service provider and they said they will put a code but they haven't( they are known for terrible customer service)

And this morning I have tested the speed and I`m getting from 10-30 mb, anyone know how I can put a code.
I dont want anyone I dont know using my internet.