Head off to your local library and see if they have a Haynes or Chilton repair manual.
You're going to need it because this is a difficult, time-consuming, messy job and requires
a lot of patience and finding where all the screws are to dismantle the unit which is under
the dashboard. There are even screws to remove that are behind the ash tray which needs
to come out in order to gain access.
If your library doesn't have one, try eBay or Haynes Repair Manuals online..
Patience, Patience , Patience for this job is key.