ThisOldHouse.com has step-by-step instructions on how to install a front door lock. Home Depot's website contains a video with instructions for this task and the lock manufacturer Schlage has several installation documents and videos on its website for its different door lock products
ThisOldHouse.com estimates that changing the door locks, also called a lock set, should take about one to two hours and has an easy to moderate difficulty rating. If the homeowner is replacing a lock set on an existing door or installing a lock on a pre-drilled door, then the task should take no more than 20 minutes.
However, if the homeowner needs to drill the holes for the lock, he needs an electric drill with a 3/32 inch bit and a 7/8 inch spade bit. Other tools for the job include a Phillips-head screwdriver, a tape measure and hammer.