Western Digital 3TB ExHD

[Okay Guys. I just bought a 3TB external HD.
I want to use this HD as a wireless saving point in my house.
I need some guidance on what to do.... I suck at Comps....


KEY INFO:
-Windows 7 Starter
-Unsecured Wifi(need to password protect files)
-Acer Aspire One Netbook (Main PC)
-Western Digital 3TB My Book External hard-drive


If you help me figure this out,
I may pay you....
Don't just link me if you want $$$
Explain it in layman 5th grade terms.


TY In advance <3​