How to get a crown and post fitted?

Only a DDS can do it. The dentist nneds to prepare the tooth and either install a preformed post and core, or take an impression and fit a fabricated post and then take an impression for the crown.
Steps. A post extends into the root of a tooth that has had a root canal and builds up the top of the top of that tooth so a crown, or cap can be placed to bring it back to full shape and function.