First, you have to take all the necessary measurements of the place where you want to create your arched entryway. It is extremely important for you to verify the measurements at least twice to avoid any kind of problems afterwards. Then, cover all the furnishings and remove all the items from the place.
After that, you have to remove the door and the drywall. Take a pry bar, lose it and remove the casing from the wall. Now, take the baseboards out and use hammer to take out protruding nails.
Select an arched-doorway kit according to the measurements you took in step 1. You can easily get the doorway from any home centre store near your house.
Make the place in the wall to place the entryway and then install all the blocks in the corners. After that, insert the screws and tighten them properly. You may have to cut the drywall in order to fit the entryway properly.
Take a knife and spread the joint compound on the entryway to cover all the holes. Apply the paper tape and make it smooth with the broad knife. Allow the surface to dry.
Now, you have to sand, prime and paint all the three pieces of kit. Place each column one by one under the arch and adjust it accordingly. Drill the pilot holes to nail the columns to make them firm and use the decorative top cap in the end to fit the entryway in its place.