How can I use it to copy and get files from other machines.

if anyone knows of this FTP command, please post all that you know about it here so I can learn more.

use the man ftp command to find out more. To find more about the commands once in ftp, use the ? to get more help
% ftp
ftp> ?
Commands may be abbreviated. Commands are:

! cr macdef proxy send
$ delete mdelete sendport status
account debug mdir put struct
append dir mget pwd sunique
ascii disconnect mkdir quit tenex
bell form mls quote trace
binary get mode recv type
bye glob mput remotehelp user
case hash nmap rename verbose
cd help ntrans reset ?
cdup lcd open rmdir
close ls prompt runique
ftp> ? ascii
ascii set ascii transfer type
ftp> quit

Further info at
http://www.wu-ftpd.org/rfc/rfc0412.txt

Easy way is to do a "man ftp" it'll have all your commands there. Or simple, connect using FTP once logged in, don't even have to be logged in. Just type help. Show you all the commands that you can use!