The basics are:
Jack the car up ...
Take the wheel off ...
Take the dust covers off the back of the caliper unit (that attaches it to a hub), and undo with one of those ¬ shaped allen key bolt removers (from Halfords)...
The caliper should slide away from the disc, make sure it doesn't hang down by the brake hose (support it by a piece of string or something)
The brake pads can be removed by just pulling them out by hand - you'll need to compress the piston in the caliper as your pads have worn down so the new ones will be thick and won't fit the disc, I use a simple carpentry G-Clamp and slowly squeeze it with that (brake fluid should rise in the fluid resevoir in the engine bay) ...
Pop the new pads back in ...
The discs are easier - undo the single little screw that will be on the disc, and remove it, and change over for the new one.
Then do the reverse, it can be done in 15 minutes, the only pain are the bolts on the back of the caliper, they're quite tight and there's not much room! You don't have to bleed the brakes this way also.
I've probably left something out there as well.