Rear end help!!

So today I just started to get a ticking sound from my passanger rear break. Then at 30+mph I get a vibration. I know my driveline isn't vibrating. Also my tires are perfectly balanced because my tires are brand new. I pulled apart the drum and found my master cylinder (I think that's what it is called) but the sleeve inside that pushes the pads in and out was pushed all the way out and won't go back in. But just any advice on where to start looking would help a lot.

 

Your master cylinder isbunder the hood, its the metal thing attached to the big black circle, with the brake fluid resevoir on top

 

Wheel cylinder

 

It sounds like ( as pointed out by DoorDing ) you may be very inexperienced with the brake system. I would get some assistance from someone that knows what they are looking at. It could be the difference between having an accident and not...

 

I know my way around disk breaks very well. But drum I try and not touch. I'm getting my breaks looked.