Setting up an FTP server

I recently got a block of 5 static ip's for my network. I have a g4 server running appleshare ip 6.3 (i think thats what it is called without looking at it) Can anybody explain to me how to set it up as an ftp server to allow other users on the internet to access it. I have 2 hard drives on it with 1 partitioned into 2 partitions. I would like to have access to all three from a remote computer outside my network. I could set this up if it were pc's but when it comes to mac's i'm a little ignorant. Do I need software to do it or will the server software and os 9.1 do it?