Firstly, measure your existing frame from the inside of your home (width & height) to identify the proper size of window needed.
Secondly, remove existing sashes (glass windows) from the inside of your home.
Break rivets to remove existing tracks and jambs.
Attach the new side jamb covers to each side with the step facing the exterior.
Place the new window into the frame from the exterior ensuring the drain holes are on the bottom of the window.
Level and secure the window in place with the 4 screws provided - 2 on each side.
Apply caulking to the interior and exterior of the joints to complete the installation.