If using Mac:
Open the Terminal application (Utilities);
On the command line, enter the ssh command: User-Mac:~ User$ ssh IP_of_your_VPS -l root
When prompted, enter your VPS root password.
If using Windows:
You can find a detailed tutorial with pictures of how to connect to the server from Windows PC using a program called PuTTY here.
If using Linux:
Open the Terminal Emulator;
On the command line, enter the ssh command: ssh root@IP_of_your_VPS
When prompted, enter your VPS ‘root’ password.