a) Shim the remaining of the doorframe after it has been installed.
b) Put the wooden shim of the door on its hinged side behind the hinge attachment point found in the doorframe.
c) Take note that your door will be attached to the rough opening permanently.
d) You should adjust the frame and shim until the doorjamb found on one its side is plumed in both sides and directions.
e) Do not forget to check if the gap is at 18 inches between the door’s edge and the doorjamb. Nail the new door with about 16 finishing nails through its hinge jamb found in the hinge location.
f) Don’t hammer the nails totally.
g) You can also install a shim behind the location of the lock strike.
h) Secure all the doorjambs with the use of about three-inch screws through the shims found at the location of the hinges found on the hinge jamb. You can continue it around the new door by securing all the other jambs using nails or screws secured through the shims to prevent altering or damaging the doorframe. Install the screws trough the shim found at the lock strike.