Close the old framed shower door.
Slide wood shims up under the old framed shower door to prevent it from falling as you unfasten the hinges.
Unfasten the retaining screws in the framed shower door hinges with a screwdriver and place them in a plastic bag.
Pull the old framed door away from the shower enclosure and take it to a recycling center or set outside to be taken away during scheduled trash pick-up. Leave the shims in place for reuse so you do not have to measure and match the gap under the door.
Fit your new framed shower door into place on top of the wood shims.
Line up the holes in the new shower door with the hinges on the shower enclosure.
Fasten retaining screws through the hinges using a screwdriver to hold the new framed shower door in place.
Remove the wood shims from under the new door and test the door swing by opening and closing it.