how to repair a cylinder head 2000 mercury villager

Drain the radiator. Remove the drive belts. Remove the accessories (alternator, power steering, etc.) Remove the valve covers. Remove the intake manifold. Remove the head bolts and the head. Replace the head bolts with new ones. Before disconnecting any vacuum or electrical lines, label both sides of the connection to make sure you reconnect everything properly.

This is a major repair. I recommend getting a good repair manual that has step by step instructions and pictures to identify parts. For me to try to explaine it via the internet allows too much room for error.

I agree with Jacobandnickolas, a repair manual from Haynes or Chilton's is highly recommended. However, if you're careful, take pictures to track your progress and keep track of parts locations, you should be fine. Giving detailed step by step instructions in this format is prohibitive. But, if you follow those I gave, and track your progress with pictures and proper labeling, you'll do fine.
Head bolt torque: Multi-stage: 1st: 22 ft-lbs. 2nd: 43 ft-lbs. Loosen them completely. Final torque is to 89 inch-pounds. Use the attached image for torque sequence.

The link below has some good pictures showing torque sequences and what needs to be removed. It also has a listing of the pertinent torque specs.
http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f802c53a2