I have included an image from the parts break down for your model.
It's a fairly cut and dry task to change the brakes on these. I do recommend lifting the back end of the tractor and removing the right rear wheel/tire. It's not completely necessary, but it sure does make doing this a whole lot easier if you do.
In the photo I included, key number 70 are the friction pucks (brake pads)
Key number 65. There are 2 of them. When you have everything taken down, remove those from the little housing they go in and clean them with some light sand paper. Put a little bit of grease or anti-seize on them when you put them back. They slide right out of the housing they're in. If they don't come right out it's because they're stuck. You can peck them out with a hammer and punch if need be.
If you have any further questions about this, feel free to ask.