TTSSH is an ssh plugin for Tera Term Telnet. ssh is a more secure method of conecting to remote computers.
Type in the name of the host you want to connect to. Make sure that you select "SSH" as the service to use.
Enter your CS account name and password, then click OK.
And you're logged in!
Tera Term also has more advanced features than the usual Windows telnet client, such as an easy cut and paste, and session options. CRF reccommends that Windows users use TeraTerm with SSH to connect to remote machines, rather than using telnet. TTSSH is installed in MRL, the Microsoft Research Lab.
TeraTerm is available from http://hp.vector.co.jp/authors/VA002416/teraterm.html. The ssh plugin is available from http://www.zip.com.au/~roca/ttssh.html. For more information about ssh in general, visit LDEO's SSH FAQ.