Car heater

I have a 2001 Pontiac Sunfire, with 2.4 engine and approx 106,000 km.
The fan / heater has 4 settings, but I only get air blowing on the highest setting. I had the cover off of the radio / heater area and was able to see the fan / heater. It appears there is some kind of oil leaking as well as this area was wet and I had noticed a burning smell when using the rear defrost.
Is there step by step instructions (pictures would be nice) some where on how to remove and replace the fan / heater. I think I can do this myself I just don't want to electrocute myself or force something to come apart (if it is not meant to be taken apart).