You first have to extract the drum by turning off the hub nut, After the drum has been extracted, you use a special tool you can rent from the auto part store, called a wheel bearing puller which will extract the old bearing, and need to be used to insert the new one. Note; Some bearing after installation, and drums placed respectively, hub nuts may be required to be torqued to correct specifications, so please check. This is important! before you may think you have completed the job.
Gary Allen, April 2007