Help, Front brake pads

[Estecks]

This may be a dumb question and I looked around the forum and FAQ and can't find anything about changing the front brake pads, I'm assuming I should bleed my brakes too so a tutorial on that would really help. Can anyone help? my bike has been sitting outside for a couple years so I took off the front caliper (also why I need to bleed the brakes) and tried using a c clamp to push back in the pistons but it is stuck, any ideas? I'm lost. The pads look thick.