I would add - if you install new linings on the rear, you must adjust the brakes initially. The pros use a special tool to do this.
https://www.amazon.com/GearWrench-3377- ... B0002SQUJ0
You then follow the instructions in the TSM to finish the adjustment using the self-adjusters. The self-adjusters must be assembled properly; they are different left and right. Again, the TSM will show you a picture that you must follow.
You can use a brake spoon and screwdriver to make the initial adjustment, but the special tool is __much__ easier, and success is much more likely.
The linings are held away from the drums by strong springs. These could feel solid with the engine off. Start the engine and the linings suddenly move easily.
Realize that you have to 1) get all the air out of the system and 2) make an initial adjustment so the movement of the pads and linings is small compared to the (not large) fluid volume the master cylinder moves. Liquids are incompressible, and gases are compressible. You need 100% liquid (fluid) in the system - no air!
Drum brakes are easy, but they are mysterious to most modern mechanics, shadetree or otherwise. Brake drums wear faster and have more moving parts than disks. The TSM will help you here. If you are flailing, suggest you replace everything for the rear brakes that's available - linings, drums, springs, self-adjusters, pawl, pins, etc. Don't cheap out on brake parts.