Go to where your court is (for example: England's court is in London, unless the player manually changes it), talk to the Minister, and tell him that you dont need his services anymore or something like that. He'll has you who is going to replace him. Select one of your companions.

After that, the companion you appointed as Minister will be at your court. Talk to him, you'll be able to send emissaries to other countries. That way you can start wars, for example, but also to do other things.

oh thank you