To install a screen door insert, pry the window pane off the door, fix the screen insert in the channels of the window, and reinstall the window pane. You need a screwdriver, nut driver and screen insert to complete the project.
Measure your window with a tape measure, and use the measurements to purchase a screen insert, available from a local hardware store. Press in the tabs on the window, raise the window from its bottom, move the pins in the channel to align them with slot holes, remove the pins and pry out the window.
Put the screen insert into the channel on the backside of the window, and turn the locking screws clockwise to secure the screen insert. Be sure that the insert faces outward. Once the screen is installed, use a rag to clean the channels that the window sits in. To reinstall the window, direct the edge of the window toward the door, move the pins along the channel to line them up with the slots, push the bottom tabs, allow the tabs to slip back, and insert the window.
Alternatively, purchase a window with a screen insert already installed. Use a screwdriver to unfasten the window that presently sits on the door, set the window aside and install the window that comes with a screen insert.