I know this is a standard answer BUT, FOR THIS ENGINE, if you had to ask, BUY THE SERVICE MANUAL. This is not a hard job but complicated in that alot of engine parts have to come off to get to it. If I were you, I would also change the Water Pump which is timing belt driven. They always have a habit of going out right AFTER you put the vehicle back together again. Just joking, but it seems like not to long after wards you have water pump problems (because of the age of the vehicle) and you have to do the whole thing over again.
GOOD LUCK