jack up the front of the car, removed both front wheels (place on axle stands, safety first!) chock the rear wheels to prevent the car moving then lift the bonnet and undo the cap for the brake fluid reservior.
to change the pads all you need to do is remove the two pins from the top of the caliper by pushing them through to the back, don't lose the piece of metal that sits on the top of the pads. if you're replacing the discs at the same time then you can wedge something between the old pads and disc to lever the pistons back into the caliper otherwise the new pads won't physically fit. refitting is the exact reverse of this.
to fit new discs you need to remove the caliper, there are two large allen key type bolts that hold the caliper in place. just take these out and move the caliper to one side but make sure it is supported somewhere and not just swinging in the wind. then to remove the disc you need a phillips screwdriver to undo one screw then the disc should come straight off. if it doesn't then give it a couple of taps with a hammer to loosen it but mind your feet because it'll hurt if it lands on your toes! before putting the new disc on make sure the mounting surface is clean by using a wire brush then put some copper-slip grease on to the mounting surface to prevent the discs sticking next time then fit the new disc and tighten up the screw with the phillips screwdriver. re-fit the caliper and do up the allen type bolt b'stard tight then slide the new pads in replace the spring clip thing on top of the pads and slide the pins in through the back of the caliper. job done, all you need to do now is the other side. once finished put the wheels back on, tighten up the cap on the brake fluid reservior pump the middle pedal a few times until it goes hard (fnarr, fnarr)
then sit back and have a cuppa and a smile knowing that you've saved yourself a fortune doing it yourself and not paying some grease monkey an arm and a leg for a job which takes no longer than a hour to do!