Few simple steps here for when it is time to change your pads. Firstly don't wait like me until they are totally worn down! This is for two main reasons. 1) you are damaging your discs and 2) you have clearly been  riding without a functioning brake for a while

A short video tutorial I put together on how to do all this:

• Take of your wheel
• Unscrew the bolt holding your pads in
• When your pads drop out have a good long look and promise to never leave it so long again

• Push back the pistons with a gentle edge (a blunt knife edge works well) until they are all the way back

• Line up your new pads and drop them in
• Screw back in the bolt