Measure the rough opening for width and height
Cut two king studs to full wall height
Mark the door opening location on the bottom plate
Cut out the bottom plate section for the doorway
Install the king studs on both sides of the opening
Cut two jack studs to support the header
Install the jack studs inside the king studs
Cut the header to span the opening
Place the header on top of the jack studs
Install cripple studs above the header if needed
Check the opening for plumb, level, and square
Nail or screw all framing members securely
Verify the rough opening matches the door specifications