Knights are used to speed up construction times, increase resource production, and lead your troops into battle. You need to build a Knights Hall to hire Knights.
Knights cost 1,000 gold to hire and have an ongoing gold cost based on their level.
Click on your Knights Hall and select a friend to hire from the Appoint Knights tab (the friend does not have to play KoC but has a +5 to skills if they do).
Then go to the “My Knights” tab and click “Assign Role” to put the knight to work.
Click “Assign Skill” to boost the attributes appropriate to their role.
When you want to wage war, you will need to either temporarily Un-Assign one of your knights (probably your Marshal since she also needs Combat skill), or have an extra Knight who remains unassigned to lead armies. Eventually, you might want additional knights to lead additional armies