How do you change the engine oil on a 1997 Geo Prizm?

The same way as you'd change it on any other car. Raise the car, put it on ramps or jackstands, remove the oil drain plug from the oil pan making sure you have a catch pan for the oil. Let it drain until all of the dirty oil is drained into the catch pan. Reinstall the drain plug, put your catch pan under the oil filter, remove the filter and let it drain. Clean the mounting surface where the old filter came off, put some clean oil on the gasket of the new filter, spin it on until snug, turn it an additional 3/4 turn, put in the new oil and off you go. Check your owners manual or the parts store to find out how much oil you'll need. If it's the 1.6, three quarts. If it's 1.8, three and one half quarts.