How to setup FTP on OS X behind a Linksys

[Ian Sights]

I'm running 10.2.2 and want to share files with a friend in Seattle. I 
know that OS X supports FTP, but I'm using a Linksys to distribute my 
DSL line in the house. I tried turning on FTP but couldn't connect to 
the internet until I turned it off again.
I know that I have a dynamic IP address, but that's ok as long as I can 
mail my friend the correct address to FTP to for the current session.
  Is  this possible with OS X? The Linksys help file wasn't much help, 
it's a little to geeky for me.

Ian