Don't know about your particular car but most vehicles have a metal cable(s) running underneath from the rear drums to the emergency brake handle/pedal. The cable/s should have an adjuster on it to tighten or loosen it up. Once you locate it, it will be pretty self explanatory in itself. Maybe some bolts to loosen and then turn this bracket thingy. Adjust it and try it out, a kinda trail and error job.
The rear brake cable splits to two cables behind the front adjuster under the rear left passenger floorboard. That's where to tighten or loosten the adjustment. Are each of the rear cables loose inside the outer black plastic shield which covers a flat wound steel support ? On a car that old the rear oor forward emergency cable rusts and corrodes so it's not free to slide inside the outer shield. Disconnect the front to rear emergency brake connection. Figure out which cable (front or rear) is jammed and replace it.
Did you adjust the pads so they were almost snug against the drums, if not then do so. Also the rear brakes self adjust each time the car is driven in reverse and then the brake is applied. However if you did adjust the pads to almost be snug against the drums then trying to adjust brake by going in reverse could be a long process. Hope this helps and best of luck in advance !!
can adjust rear brake more thats how e brake work when your adjusting rear brake thru slot on back of dust cover to where wheel is hard to spin with one hand e brake should work great then only a few cars able to adjust cable which is under car can look for that most likely wil just need to adjust rear brake more type into search box
how to adjust rear brake shoes