Chrome – How do add a certificate from a self-signed server to trusted certificates in Chrome

I have a dedicated server with a wiki and want to secure it so nobody can read my articles by sniffing my pages.

I do not want to pay for a valid certificate so I created a self-signed certificate. But always when I access my page through HTTPS I get a SSL Error with the following message:

The site's security certificate is not trusted!

How can I manually add the certificate to my trusted certificates or prevent that message from showing?

This is my server and I trust the certificate as long as it does not change.