Security on bluetooth/wifi

Can someone access my files or what I'm doing w/o a prompt coming up on my computer to tell me that somone is in fact doing so? Would I always necessarily have to gant permissoin, or is there a way to bipass that? My bluetooth and wireless were both on and other devices were shoing up in the finder window. Then some weird stuff that I've never seen happened. Word froze up, some pop up tried to show up but was blank white. It was odd and now I'm worried slightly. Thanks!!!