How do i replace a head gasket on a 1998 saturn sw2

In the real world this job is beyond the tools and abilities of anyone who asks the question. You have to have a lot of mechanical experience and a good set of tools to undertake this job. There are dozens of steps in the procedure, you need a service manual with pictures.

In the real world it will be cheaper for you to find a good used Saturn 96-98 DOHC engine and swap it in. That again is a task beyond the scope of anyone who does not have a hoist, jack stands, and a good set of tools.

There are lots of Saturn repair videos on youtube and I am sure you can also find a video of someone removing the head of a 4 cylinder engine. The process will be about the same for any 4 cylinder, including Saturn.