Welcome. Changing the rear shoes is a pain to do, but I can help you with a couple of warnings and tricks. First that large spring has alot of power. Second, it is possible to pop one side of the wheel cylinder out. The tool J38400 is pictured below. I have used a couple of screw drivers and a set of vice grips and it has worked.
TipCompletely retract the brake shoe adjuster to ease removal of the adjuster spring.
Brake Shoe Adjuster
Clean and apply high temperature brake lubricant to the adjuster threads.
Brake Shoe Retractor Spring
J 38400 Brake Shoe Spanner and Spring Remover
Brake Primary Shoe
Brake Secondary Shoe