You will find some good "on-line" tutorials on Mac OSX's Terminal use at http://www.macdevcenter.com/pub/ct/51
You will find some more excellent tutorials and the like at http://www.osxfaq.com/
As Grinler says, Terminal is essentially a "shell" that gives you command line access to the unix underpinnings of MacOSX. You can use it for remote access purposes of the type which you speak though - see http://www.columbia.edu/acis/software/inet/osx-terminal.html
for some instructions.
(I'm assuming you mean "Terminal" as found in OSX. From memory there was once a program called "Terminal" for the Mac, or was it "MacTerminal" which ran under much older versions of the OS (like system 6 and 7 back in the late 80's and early 1990's) and was purely and simply a remote access / comms client.)