In general, it's easy to change the cartridge on a home printer. On mine, I just lift the front to bring both carts to the center and snap the old one out. Then, I peel the film off the new cartridge and snap it in place.
Always remember to run a cartridge alignment utility when you change carts so your printed material will be properly calibrated. Every cartridge is a little different, so the settings for the printer might change just a bit.
Changing the cartridge on an office laser printer is a whole different issue, and one best left to people who know what they're doing. It's not generally something anyone in the office can do. Leave that to the tech guy or girl.