Ok. You could use an FTP server for that and it is quite a fast protocol compared to others.
To start I suggest you download and install Filezilla, as a service which starts on windows boot.
SourceForge.net: Downloading ...
Once that has installed, open it and go to Edit - Users. Click Add at the side and type a name, then set a secure password and click on Shared Folders, click Add on the left. Select the directory or drive you would like the user to have access to. And set appropriate permissions at the side. Then click OK, and to test the setup type
ftp://127.0.0.1:21 into your browser and type your username and password and see if it gives a listing of files.
Next you will need to port forward the server through your router, this guide will help you.
Port Forwarding for the Belkin F5D8233-4
Then you should be able to access your files using a dedicated ftp client from another PC or a suitable browser, however if you don't have a static IP your IP address will change sometimes and you will have to keep finding it. If you don't have a static IP a service like
DynDNS would help as you could use a hostname to access your PC instead of the IP. If you need help with that please ask.