jack car up put on a jack stand slide under it remove transmission oil pan one bolt at a time with a big catch pan under car not hard really easy do at home thing but you can find most car repairs by typing how to so type into search box how to replace transmission flush or how to drain transmission fluid add video and might even find one to watch
type it like
How to change transmission fluid 1997 Cadillac Seville
How to change transmission fluid 1997 Cadillac Seville video
might even find
repair manual 1997 Cadillac Seville PDF