Camera work: aperture

Today it's 'aperture'. I know the concept from my old 35mm and medium format days, but with these darned tootin' digital cameras, I'm just trying to figure out which buttons can get the effect I'm after.

So, a quiet house, the lads are out and a cup of coffee brewing. Here we go! By the way, this isn't meant as a tutorial for anyone but myself, I'm writing this down to remember and haven't actually tried it out yet!

1. Turn the camera on.
2. Turn the top left dial on the camera body to 'A'. This puts the camera in Aperture mode.
3. Turn Auto/Manual switch on the lens (A M) to the M. This puts the lens in manual mode.
4. On the front left of the camera body, turn the Auto Focus/Manual (AF M) button to M to tell the camera you're taking over manually.
5. Turn the notched dial under the On/Off switch left or right, depending on the aperture you want.
6. The smaller the aperture number next to the 'f', the more light the lens lets in and the camera only focuses on the subject on a particular plane (more depth of field). The higher the aperture number, the more light the lens lets in and the more of the framed image will be in focus (less depth of field).
7. Once that's all set up, point the camera towards your subject and use the zoom ring (turning that ring, shifts the numbers on the lens barrel) on the front of the lens barrel to get closer to your subject via the camera.
8. Then adjust the focus ring (the slimmer of the two rings) to put the subject in focus.
9. Press down on the Depth of Field preview button on the bottom right front of the camera. (P.S. Don't get this mixed up with the 'fn' button above the DoF button.

Some websites that helped me figure out all of this and more:
Wikipedia
Nikon D90 for Dummies and their Nikon D90 cheat sheet
Focusing Tips with Phil Steele