Pageant is an SSH Authentication Agent for Windows. You can load your SSH private key(s) into Pageant and when you attempt to make external SSH connections using PuTTY (and certain other tools) it will attempt to use those keys. Typically, you will use PuTTY to connect to a remote host via SSH.
Adding your private key to Pageant
Install and start the Pageant application and you should see a window like the following:
Once your private key is loaded into your Pageant session and your public key has been loaded on the remote server then you should be able to log in to our servers. Install, and start, PuTTY and the following screen will appear.
To set up a connection to a server type the <user_id>@<server ip>
path into the Host Name (or IP address) input box.
To open the log on to the remote server click the Open button.