Measure the rough opening
Check that the opening is square, plumb, and level
Mark the window height and width on the wall framing
Cut the wall studs at the opening
Install the king studs on both sides of the opening
Install the jack studs inside the king studs
Cut and install the header between the jack studs
Install the sill at the bottom of the opening
Install the cripple studs above the header
Install the cripple studs below the sill
Double-check all dimensions before nailing
Secure all framing members with appropriate fasteners
Verify the rough opening matches the window manufacturer’s specifications