Soak replacement reeds in water for an hour. Take the reeds out and press all excess water from the reeds.
Inspect the arm of your wicker chair for warping. Soak a towel in water and place the towel over the warped section of the chair arm. Remove the towel after an hour or two and reposition the reed back into place. Place a few nails into the reeds underneath the arm of the chair and let it dry.
Inspect the arm of your wicker for broken or missing reeds. Look for the starting point where the missing reed broke off. Cur the broken piece and nail the remaining reed piece down with a small nail or two.
Begin a new starting point by taking a reed and nailing it underneath the arm of the chair. Begin to follow the design of the chair, periodically tightening and nailing a nail underneath the arm to secure the reed in place.
Place the chair in a room temperature environment or outside where it's exposed to direct sunlight and let it dry.