Summarize the following:
To repair your bumper, you will need fiberglass resin, fiberglass matting strips, and a liquid hardening agent, along with plastic or wooden sticks to help mix the resin and a brush or other applicator to put it on the bumper. You can purchase these separately or in pre-packaged fiberglass repair kits. Look for the materials at auto supply stores. Grab your cloth matting and hold it up to a damaged area. Using a fabric marker, make a line on top of the cloth indicating the crack placement. Then, take your fabric to a solid working table and cut it using a precision knife. So you have enough overlap to support the fiberglass, leave about 20 mm (0.79 in) of space around the marked area. Repeat this with each crack. Grab a small container and pour in the amount of resin you think you’ll need to cover a specific piece of fiberglass matting. Then, check the instructions on the back of your resin container and apply the recommended amount of hardening agent. Using a plastic or wooden stick, stir the substances together until they are well mixed. Once combined, most resin mixes stay soft for 8 to 12 minutes, after which they become unusable. Cover the back of a damaged area with a sheet of fiberglass matting. Using a brush or other applicator, cover the entirety of the cloth and about 2.5 inches (6.4 cm) of the surrounding area with the resin mix. Repeat this with each crack, then let the matting cure in a moderately warm area for about 2 hours. For extremely large cracks, you may need to apply matting to the front of the bumper as well.

Summary:
Purchase resin, hardener, and cloth matting strips. Cut the fiberglass matting to the size of each cracked area. Mix the resin and hardener together. Apply the matting to your bumper using the resin mix.