I am a novice backyard mechanic. The extent of my previous works include water pumps, starter motors, radiators etc... All pretty simple jobs. I have a 1998 cavalier Z24 twin cam 2.4 liter with a blown head gasket (car has 120,000 miles on it) . I know its blown because my mechanic told me so. It sputters and there is a distinct smell of glycol coming from the exhaust. I am pretty good with following directions. I wanted to know if anybody could give me step by step instructions on how to replace it?

That's like the hardest one to do in a Cavi. :)...

Pretty sure you can buy a manual at a parts store...

Two very important tips with the 2.4L... when installing the cams turn the crankshaft 90 degrees (3 o'clock position). This puts all the pistons half way,which leaves room for the valves to open until you get everything in time.Then when it's time to put chain on and the cams are set in time turn the crank backwards that 90 degrees to 12 o'clock... and, make sure the cam followers(lifters) are spongy and not pumped-up solid.They will not let the valves close and will destroy the open valves,piston, and possibly the head

Try this site but I wouldn't suggest doing it yourself...
WikiAnswers - How do you replace a head gasket (http://wiki.answers.com/Q/How_do_you_replace_a_head_gasket)

Let me know how it turns out!!

Have you noticed any loss of coolant? Has the vehicle been overheating? What did your mechanic do to determine that the head gasket is bad? The only reason I ask is because I hate to see people do more than they need to.