I bought a brewers best beginer kit and didn't realise it didnt come wit anything to sterilize it with, just with a cleaner solution. But my question is what do I put in the airlock?
First it is hard to sterilize in a brewing situation, but we do sanitize a fair bit.....
Buy a good sanitizer solution like Star-san and mix it for use.
I use star-san in my airlocks but a lot of people use cheap vodka. Really anything that won't contaminate the beer should be good. Boiled cooled water is also good.