Ok
Frame the wall just like you did the other two except the top plate will have the 3-1/2 overhang on both sides.
Decide where you want the door to be. If you already have the door and jamb, measure the width of the door.
Lets say you have a prehung unit that you bought at lowes or HD. A prehung unit will be the whole enchilada...door, jamb, casing. hinges etc.
These are normally called "split jambs" because you can take the door off and the jamb is two pieces for ease of installation.
Now lets say that the width of the door itself is 24". The opening you want to frame will be 26 - 1/2. This gives you room to play with the door since it will not fit snug.
Now measure the height of the door and add say 3/4" to that. The total of these two is the height where you want the bottom edge of your header.
Crap let me draw it out.....wait one.