If all you want is to access it from inside your home network, it's easy. Set up the Windows drive you want to hold the files with sharing. Password it if you want, but unless you have folks that might get to it that you don't want to, it's not required. If you have a wireless router, I'd password it, but if your network is all wired and you trust everyone with access, skip it.
Now use Finder->Go->Connect to server and give the ip address and sharename of the disk you just set up on the windows box. It should now ask for any password you set up and then mount the location. Now you can read/write to that just like any drive.
If you want to access it from outside your home network, that is more tricky and not secure. That's also beyond my ability.