How to fit a “pocket door”

Pocket doors can usually be adjusted by turning/twisting an adjustment screw at the top (sometimes a wheel at the bottom depending on the door). The door should allow for this adjustment somewhere without removing anything.

A pocket door is a door that slides into the wall as opposed to opening in or out as a regular door would.

A good comparison would be the sliding doors as most mega-marts or large stores that slide open when you walk towards them or if you're a fan of "Star Trek: The Next Generation". The doors throughout the ship are "pocket doors" (except our pocket doors don't make the neat hissing sound when the open).