How do you change the spark plugs on a 1993 cadillac seville

How do you change the spark plugs on a 1993 cadillac seville
Which engine: 4.9L or 4.6L?

Actually both are about the same, just the exact location is slightly different.
On the 4.9L, they are screwed into the side of the cylinder head.
On the 4.6L, they are screwed into the top of the cylinder head, down through the top of the valve covers.
Servicing the rear, or right bank, is difficult access. Take your time and move whatever components you need to. Once you've got the old plugs out, apply a dab of dielectric to the new plug, coating all the way around where the spark plug boot rides. This step can alleviate corrosion that can lead to a misfire.