How do I access my VPS or Dedicated server using ssh with root user?

What is SSH? What is SFTP?
SSH (Secure Shell Protocol) is a secure replacement for telnet and is used to open a terminal session on a remote host (i.e., a remote computer). SFTP (Secure File Transfer Protocol) is a secure replacement for FTP and is used to transfer files between your computer and a remote computer. The SSH Client for Microsoft Windows provides both SSH and SFTP connections to a remote host. The advantages of SSH/SFTP over telnet/FTP are:
1. All information transmitted between your computer and the host is encrypted. This protects your password during login as well as information transmitted after logging in.
2. If available, you can use a publicly published “fingerprint” for a host’s “key” to verify the host’s identity.