PuTTY is a tool which allows for SSH connections. You only really need it for Winodws.
To connect to a certain address, just put it into the box as shown. If you know that you are going to connect to that address often, you can save it for later (you have to put a name into the Saved Sessions box). When you need to access it again, select it from the list load it. Press Open to start the session.
If PuTTY has been added to the path, run it as follows:
to just reach a prompt for the username and password. If you are prompted about something like accepting a key (I cannot remember exactly what it says), just accept.