Plugging your Pi into a router. Routers can be had from 20USD and up and are what I'd use since I'd want a WiFi central to my system.
I live on a canal boat and I would like to build a file server that works with only USB ports. I would like to try and make it wireless. I was thinking to buy a WD My Passport 4TB and then buy a Rapsberry PI and connect the Hard Drive and download the needed software. I just cannot figure out how to make it wireless. What software should I need to access the files on iOS, Chrome OS, Windows and Linux?