To braid challah, start by dividing your challah dough into three equal portions. Roll each portion into a long, thin rope, making sure they are of equal length, and then pinch the three ropes together at one end. Next, braid the ropes together by crossing the right rope over the middle one and then the left rope over the new middle one, repeating this process until you reach the other end. Finally, pinch the ends together and tuck them under the loaf to secure the braid, and let the braided dough rise before baking according to your recipe's instructions.