Sharing Mac hard drive over the Internet to a PC
You may get better help on the Windows side of this problem from Super User.

As for the Mac side, mounting the drive in a folder in your user directory should work and is a good idea. However, you used the wrong command. ln -s makes a symbolic link, like a Shortcut on Windows or an Alias on the Mac. You can mount the drive temporarily using the diskutil mount command. There is a way to do it permanently, but I don't know how to do it offhand; you should ask a new question about that.