If you want to start an FTP server and are wanting to use the built-in one that comes with IIS, DON'T USE IT!!! If you really want to, just go to add/remove programs and click on add/remove Windows components and check the IIS box. Click details and just pick the FTP server.
I suggest going to download.com and looking for Serv-u or G6 ftp server and try those. The one that comes with windows doesn't let you configure much and can be a pain in the butt to set up. The only good thing about the windows one is that its free since you have already paid for the OS. I think the third-party shareware ones are better. Other people may recommend using WarFTP. I personally use G6.