What you need:
- FTP server
- Forward port on router to PC
For an FTP server there's a large number available. Most are not free. If you can, stay away from the ones built into Windows (2k Pro, XP Pro, and the servers). They are lacking in features compared to other ones that you can get...
What internet access do you have? DSL or cable? The more your IP changes, the more difficult it is to host an FTP properly. Not only that, if your router is the one that connects to the internet, most dynamic IP services won't work, you'd have to go to their page and enter your IP manually for people to get to you. Say you go to
www.no-ip.com and you get the name of jungle.myftp.org from them. In order for that name to work, they have to have your IP. They have a piece of software that runs on your computer, but if the router is the one that connects, not your computer, then you go to their site and enter your IP into a form and it gets updated...
With all that in mind, you need to host files. So, you need to have some space on your hard drive(s). Something else you will need to keep in mind is to not allow anonymous writing to your FTP. If you do, you could end up losing all your hard drive space in hidden and undeletable directories.
Hmm... I'm not sure what else to say. There's a number of other things to think about, but you don't need to think about them until after you figure out how to get your router to work and your IP/name. You can try as many different FTP servers as you like, once you find one that you like, keep using that one.