Anyone can build a wall and add a framed door with the right instructions. It's a subtly decorative way to have an opening into another room and isn't the most complicated carpentry task around the home.
In order to complete this task, you'll need several pieces of two-by-four wooden lumber that you'll then measure and cut to fit the dimensions of your wall and door.
Prepping the Plates
To get started, measure and cut two pieces of two-by-four lumber to the length of the wall section that's being built. This will eventually be the top and bottom plate of the wall you're constructing. Get the opening measurements for the door you purchased. These can be found in the materials that came from the manufacturer. If you don't have them, try to find the measurements online.
Once you have the measurements, mark the width of the door on both the bottom and top plates. Then, add an additional mark on both of the plates for 3 inches and for 1.5 inches on each side of the opening. The 1.5-inch marking is on the inner part and will be where the jack studs will go for the door frame. The 3-inch outer measurement is where the king studs will go.
Cutting the Lumber
Measure and cut the wall studs to the same length as the wall height, minus the 3 inches. Take the top and bottom plates and nail the wall studs every 16 inches along the width of the plates. Do this everywhere except where the rough opening of the door, king and jack studs are marked. Measure and cut out two more studs to be the same size as the previous wall studs. These will be the king studs, so nail them into place using the measurements you marked out for them.
Cut out two jack studs that will be the same length as the height of your door opening, minus the 1.5 inches. Nail them into place inside of the king studs. Once that's done, make the header of the door by cutting a two-by-four so it equals the distance between the king studs. Nail it flat to the top of the jack studs.
Cut another piece of two-by-four to fit the distance between the top of the header to the bottom of the top plate. Place it as a cripple stud between the top of the plate and the center of the header and then nail it into place.
The New Wall
Raise the wall you constructed into place, screw the bottom plate to the floor and then nail or screw the top plate to the wall structure. Your new interior wall and door frame are now complete and ready to be covered.