Sounds like you have a pretty firm grasp on what you need to do, but i'll throw a few pointers your way.
1. Change the oil with the engine warm. It flows alot better that way.
2. Get yourself an oil change pump. It has a tube that goes down the dipstick and sucks the oil out of theh sump. West marine has a good selection: http://www.westmarine.com/webapp/wcs/stores/servlet/categoryg/10001/-1/10001/170/169/6/man/asc/0/grid
I would get either an electric one or the one that runs off a drill. I have the topsider vacuum pump and it sucks. I'm assuming you know where the dipstick is.
3. You'll need an oil filter wrench. You can pick one up at any auto parts store. While you're at the parts store, go ahead and get your new oil and filter. I use the Mobil 1 filter, but I also hear good things about the K&N oil filters.
4. Pour some fresh oil into the new filter before you put it on and coat the rubber o-ring on the new filter with oil (just use your finger).
5. When you put the new filter on, it doesnt have to be REALLY tight. Get it hand tight, and then tighten it 3/4 to one full turn with the wrench.
6. When you pour in the fresh oil, put in 1 quart less than the engine's oil capacity and then check the level on the dipstick. Then add oil 1/4 quart at a time, checking the dipstick each time, until you reach the full mark on the dipstick.
7.To check the level, remove the dipstick, wipe it with a rag, reinsert it, pull it back out and read the level on the dipstick.
OK, here's a non-detailed list of the steps:
1. Suck the old oil out with your pump
2. Remove the old filter
3. Fill the new filter with oil, coat the o-ring, and install.
4. Refill the engine with fresh oil.
5. Check the oil level
6. Run the engine and check for leaks.
7. Check the oil level again and top-up as necessary.
Changing the lube in your lower unit is even easier. Here's a page with pretty good instructions: http://www.brokeboats.com/lulube3.html