timing belt change on 1999 Mercury Mystique

How do u time the crankshaft timing with the camshaft timing when changing the timing belt?I think mine is off because my engine idles rough.Want to change the belt but not sure how.Thanks

1 answer
This is a complex job that would be too difficult to explain online. Engine rough running is typically not caused by a defective timing belt. Do you have a check engine light? Have you pulled the diagnostic codes? Steps to try first.