At my low level of expertise, the only way I can share a mounted external drive from Ubuntu 14.04 to Windows computers in my house is to use the Samba GUI to share it, then edit smb.conf to add "force user = (my username)", and access settings as "Allow access to anyone".
Any attempt to restrict users, or define users, results in failure and seems to increase the difficulty level of doing this from "something I can do" to "something I will have to dedicate three or four full days to researching and understanding and experimenting with."
The end result is that any Windows computer connected to my WiFi can find the shared drive on the network, and connect to it without a password.
The shared drive only contains media files (music and movies), but I've enabled reading and writing, because the end goal is to let myself add music to the server without having to use the Ubuntu box, which is intended to just sit quietly without a monitor, etc. and act as a server.
This feels unsafe, but I don't know if it is unsafe. My wifi uses WPA2-Personal with TKIP+AES for security.
If this is a terrible and wholly unsafe idea, pointers on where I can find an explicit step-by-step guide to setting users for Samba to work with Windows 7 and 8 would be appreciated.