How do i setup SFTP of Xserve running snow leopard?

Hello everyone, my server currently only has FTP that i used to upload simple jpegs and stuff when i wasn't anywhere near it but now i may need to upload more sensitive info and i would like to know how to setup this service. Using the Server Admin Application i click on my server then add service + icon and on the list of services SFTP is not listed. How do i go about setting this service up?