If you do not have access to a mac or linux OS then you will can access the servers using the horizon desktop. Log into horizon and select the remote desktop option.
Once you are in you can click the menu button on the bottom left and search for "putty". Click the icon as shown below.
When the window opens you can enter your login details. In the field denoted "host" enter the IP adress that you have been provided (e.g. 10.18.0.11). Then click "open"
You will then be prompted with a security alert on which you should click "yes".
Next you will see ther terminal screen where you should first enter you username (e.g. jphelan) and hit the enter key on your keyboard.
Finally you be prompted for you password. As you type there won't be any characters printed to the terminal, don't worry it is still working, so keep typing. Don't forget to hit enter after typing your password.