you could have several problems. check and see that your master cylinder is covered tight. i lost pressure through my cap at one time and it was like i had no fluid at all.

your drums have eccentrics (sp?) on the back to adjust the shoes closer to the drum. it is a long process requiring much patience to properly adjust them. jack and brace the rear of the jeep, block the front, and put the trans in neutral. loosen the lock nut with an open end wrench and turn the eccentric (needle nosed vice grips work good here) to the front of the jeep as far as you can. this should push the shoes into the drum. now have someone try to turn the tire you are working on while you loosen the eccentric. you want the brakes to feel like they are dragging a little. repeat the process for the other side and road test.

if it is still non functioning, i would find out if the master cylinder is moving enough fluid (weirder things have happened.) *then* i might take it to a shop, but only after i had done all i could...