Inside the brake,there should be an arm,attached to the rear brake shoe;it'll have a bennd at the bottom end that the tab on your brake cable will fit into. The spring will push against the end of the "arm",keeping the cable located as well as helping the brake cable return when you release the E-brake. That spring is pretty stiff,you might have to work to get the tab far enough from the end of the spring to slide it into place on the end of the arm. I try to pull up enough slack to clamp a small pair of vise-grips onto the cable to hold the spring back an inch or so.
Ince you get the cable connected,you might need to clip the cable housing to the backing plate;some trucks use a clip similar to the kind that holds your crankcase breather into the air filter housing in your newer cars;some use other kinds,but they all do esentially the same thing.The housing pokes through the backing plate a little ways,and there'll be a groove visible in the end of the cable housing,just inside the baking plate. That's where the clip will go. The flatwasher you mentioned will keep the cable housing from pulling through the backing plate,and the clip will keep it from pulling back out.That's about it;make sure the axle end of the cable and housing is just long enough to move with the axle as it travels through its full range of movement without being pulled tight or being pinched. Make your cable adjustment,and you're good to go.
