To replace a door, refer to Lowe's do-it-yourself for a step by step guide. Replacement is not very difficult. To replace just the door, tools and material required are: a new door, hammer, screw driver, tape measure, pencil, combination square, saw horses, clamps, chisel, a door lock installation kit, a drill with bits, circular saw, level, work gloves, dust mask, safety glasses, plane, shims, cardboard, and a utility knife. Before removing the old door, take a few measurements like the width and height of the door and use them to purchase your new door. Check the bottom clearance to correct the changes in the flooring. Measure up from the floor at both the edges of the door and mark at 10 inches. Take out the old door and put it on top of the new door. Mark the hinges and the lock on the new door. If the door is a little wide cut along the non-hinged side. For the floor clearance, use the marks we made on the sides. Transfer them onto the new door. Mark at 9 7/8 inches below that mark to account for 1/8 inch of clearance. Cut along a straight line with a circular saw. Use a hammer and chisel to cut around the marks for hinges. Then make screw holes. For the lock you can use the template kit. Line up the jig with the mark and attach it to the door with the screws. Drill the hole for the lock according to instructions. Paint the door if needed. Remove old hinges. Hold new hinges in place to check the position. Attach the hinges with screws. Then set the door on the hinges. You can put some shims on the floor to hold up the door. Line up the hinges and insert the pins. Check if the door closes properly and make any necessary adjustments. This video really makes it very easy to replace an old door.