First, check to see that you hav rear brakes that are properly adjusted and working. Be sure to loosen the E brake cables at the handle before making a brake shoe adjustment then take up cable slack until you have a good E'brake handle with about 4 - 5 clicks.
Release the handle and have someone push on the brake pedal while you listen for the rear shoe movement if not, then check for fluid to the rear wheel cylinder by loosening a line at the cylinder one side at a time you should get a good squirt. Be sure to catch this fluid in a shop rag and not get it on any painted surface. Also, look the wheel cylinder piston movement.
If you do not have good flow, tighten the line and loosen the rear line at the master cylinder port, push on the brake pedal confirm you have fluid there. ~Alan