Article: Since you previously marked the height of the bottom of the header on the king studs, you can now line the header up with those marks and nail it to the king studs. Use at least four 12D nails on each side. Using the marks on the top and bottom wall plates where you previously placed a K for the king studs, attach the plates to the king studs. Again, use 12D nails.  Make sure that each connection is flush and perfectly perpendicular as you go. If you are building the frame for the entire wall while framing the doorway, then this is also the point where you will install the rest of the wall studs. Now that the header, king studs, and bottom wall plate are together, you can install the trimmer studs. If you have not yet cut the trimmer studs, double check your measurement by measuring from the bottom of the header board to the top of the bottom wall plate. Using 12D nails, nail the trimmer studs from the bottom of the wall plate as well as to the king studs. When nailing to the king studs, nail from the trimmer stud into the king stud, so that in the event of any protruding nails, they’re inside the wall rather than inside the doorframe. Your half cuts in the bottom wall plate should now be flush with the edge of the trimmer studs. Finish cutting away this portion of the bottom wall plate so that the space remains flush with the trimmer studs. Now that you have the rest of the doorway framed, you can attach any last cripple studs if you had a gap between your header and wall top plate.

What is a summary?
Attach the header to the king studs. Attach the top and bottom wall plates to the king studs. Attach the trimmer studs. Finish removing the half-cut bottom plate piece. Attach any cripple studs.