This guide assumes you have already generated a key pair and had the public key added to the authorised keys on your server. If not please refer to the article on generating keys.
- Open Putty, and click on Connection --> Data, and enter the username (usually root) in the Auto-login username field

- Expand SSH and click on Auth, and browse and select your Private Key file in the Private key file for authentication field

- Click on the Session and enter your IP address into the Host Name field and the Port into the Port field.
- Enter a name you will remember the server by in the Saved Sessions field.
- Click Save.

Once this connection is saved, every time you open Putty, simply select the server in the Saved Sessions box, click Load, and then Open. This will log you into your server using your Key set.