It's not complicated. You won't need any special tools, although a compressor can be good.
Take out the brakepads.
Take off the caliper, be careful with the brake lining, have something ready for collecting the brake fluid. (It's an excellent paintstripper...)
Try to get the pistons out. If you have a compressor, put a piece of wood between the pistons (they'll be pushed out quite harshly) and blow air into the calipers.
Mark the pistons so you can put them back where they sat. Pull out the rubber seals, and start cleaning the calipers and pistons, use proper brake cleaner or spirit.
When assembling, lube the seals and pistons with brakefluid.
Drain the master cylinder completely by removing the cap (once again, beware of the fluid). You'll have loads of air in the system anyway, so it's a good opportunity to change the fluid.
Push the pistons completely in, put the calipers back, tighten up the bolts, brake linings.
And now the fun stuff, bleeding the brakes
Fill up the M/C, different schools, either pushing the fluid from the calipers using a syringe or similar, or fill from the M/C and bleed the normal way. Air can get trapped where the linings connect to the M/C, so you might try to bleed the system there as well.
If this explanation's not enough, I suggest you download the workshop manual, which you'll find somewhere here.
Good luck!
