Now that the first wall is done, you have the general idea, and the next two will be easy. Just remember to measure each wall's length 5-1/2" shorter than the foundation (for 2x6, or 3-1/2" if you're using 2x4's).
When you stand each wall up, you will place it against the 3-stud corner of the previous wall, so make sure to measure your anchor locations appropriately.
After standing the wall up and tightening down the anchors, you will want to make certain the 3-stud corner is perfectly plumb, then nail the new wall to the previous one at the 3-stud corner. Make sure it doesn't throw the diagonals out of square when you do this. If so, adjustments need to be made!
Use temporary bracing where necessary to keep the walls as straight and plumb as possible. I even used short temporary braces on the joints of the top plate, since it wasn't doubled yet.
When all three walls are finished, it should look like this, although you might want to read the next section on "building the pedestrian door" before you finish.
