This video demonstrates how to caulk windows. For this project, you will need the following: a tube caulk, a putty knife, scraper, a knife or scissors, paper towels, a long hanger or a nail, a caulk gun, a small plastic spoon or a popsicle stick. Begin by loading the caulk gun. Scrape away the old caulk to clean the area where you will be caulking. Clip off the tip of the tube of caulk. Puncture the seal with the hanger or a nail. Slowly caulk the area that you want to fill, by running along it, making and even seam. Smooth it out with a spoon, popsicle stick, or your finger. Then, clean the gun, your hands, and other surfaces with paper towels.