Clean out the crack. Use a garden hose with a sprayer nozzle and a wire brush. Remove all the loose asphalt in the crack. After it is cleaned, let it dry.
Put a tube of asphalt crack repair caulk into a caulk gun. Cut the top and puncture the inner foil seal.
Caulk the crack with the crack filler. This works best on a warm sunny day when the asphalt is hot.
Seal the asphalt after the crack filler has dried. You can use a normal asphalt sealer from you local hardware store to accomplish this. Spread it on with a broom and let it dry.