f you're using Windows XP and IIS 5.1 (I'm assuming you are), if you don't see a "Web Sites" folder, you don't have the FTP service installed.
To install the FTP service:
Go to Control Panel, then "Add/Remove Programs"
Next Choose "Add/Remove Windows Components"
Next choose "Internet Information Services (IIS)"
Click the "Details..." button.
Choose "File Transfer Protocol (FTP) Service"
Click OK a bunch of times. You may be prompted for your Windows XP CD.
That's it. Now when you go back to the Internet Services Manager console, you should see a folder that says "FTP Sites". Right-click and choose New, then FTP Site...
Setting up an FTP site will enable others to get files from you via FTP, or to upload files to your FTP site.
Your ability to use the FTP protocol to get files from other people is not dependent on installing the FTP service in IIS.
Hope this helps!
EDIT: To secure the FTP and enable SSL,
Enabling SSL in IIS on Windows XP Professional