if you chose not to install WU-FTP when you installed linux, then grab the rpm and install it. To make the program start in RedHat you can type setup choose services and scroll down to the bottom and put a check besice it. When your system reboots, you'll have a running FTP server.
To start without a reboot I believe you would want either
service ftp start
or
service wu-ftp start
Hope this helps.