I've done both the Transmission and Transfer Case. The TC is pretty straight forward. The transmission is a messy job, but pretty simple. (If I can do it, so can you

)
You need to get a LARGE oil pan.
You then loosen all the screws, but just a little.
Go to one side of the tranny case and take all the screws out of that side only. It's sealed with RTV, so it probably won't leak out.
Carefully pry that side open with a screwdirver and let the oil drain out the side as much as possible. Then remove the rest of the screws and drop the case.
There are actually 2 different filters in the transmission. One is a flat filter with some sort of mesh inside. The other looks very similar to an engine oil filter.
When you replace the filters, make sure they are properly seated, then seal the tranny with RTV and put the screws back in.
The fluid is added in the engine compartment. (Be careful not to overfill).
Remember to check it for leaks afterwards.
Hope this helps.