We recommend using the program PuTTY to access SSH. You can download it here: http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
To access your VPS via SSH:
Run PuTTY, enter your VPS IP and use port 22 (which is the default SSH port)
Click Open, a dialog window will open if you are connecting to the server from this computer for the first time. Accept the connection by clicking Yes.
Once SSH connection is open, you should see a command prompt asking for username. Enter "root" as the username. 
Use your root password as the password. You will not see your cursor move and the password will be invisible as you type it.
Once you log in, you can run various Linux commands to interact with your VPS.
Please be noted that clients holding a KVM VPS service must install an OS before they can access their VPS via SSH.