How do you change a nebco shower cartridge?

To change a Nebco shower cartridge, first, turn off the water supply to prevent any leaks. Remove the handle and the decorative cover to access the cartridge, then unscrew and pull out the old cartridge. Insert the new cartridge in the same orientation as the old one, secure it in place, and reattach the handle and cover. Finally, turn the water supply back on and test for leaks.