PuTTY is a free and open source remote shell client. It is commonly used on Windows, which does not come with a built in SSH client. You can use PuTTY to connect to your server over SSH

PuTTY can be downloaded from its download page. Most likely you'll want to use the latest release version:
PuTTY 0.61 download link

Further Reading:
Connecting through SSH
Creating a SSH Tunnel