You will need to download a program to make a command-line terminal connection. A typical choice is PuTTY, http://www.chiark.greenend.org.uk/~sgtatham/putty/. You can download and run the Windows installer, or you can just download the executable of the program itself, putty.exe, and put it directly on your desktop. When you start PuTTY, you will be presented with a connection screen. Assuming you want to make your first connection to blackjack, enter blackjack.jacks.local in the Host Name field.
When you click Open you should see the black PuTTY terminal window appear and then a message similar to the following:
This message about the encryption key should appear only the first time you connect to a given server from a particular computer. PuTTY is an encrypted protocol, but the initial connection has to be made in the clear to transfer the key. So click yes. Then you will see the login prompt for the server. Enter your username and then your password. Note that no characters will appear at all as you type the password.
When you have successfully logged in you will see the motd and the command line system prompt.
For the Mac OS you can use the Terminal app in the Utilities folder under you Applications folder. One way to quickly open Utilities is from the Go menu of Finder. Then go to the Terminal application and open it. This brings up a local command line window on your Mac. From that command prompt, use the ssh command to connect.
Once the terminal prompt is available, if you wanted to make a connection to, for example, blackjack, type a command like:
but substitute your username on the cluster for the example (