How to add a dormer to the attic level

[johnnyphuho]

Hi all,

I am new here and just recently purchased the Home Designer Pro 2014 and still learning. I am trying to draw the Cape Code house as the picture below and I am getting stuck. This cape code house has a walk up attic and there is a dormer already built in the back. I am trying to redraw this so we can finish the attic with 2 bedrooms and a bath. I understand that Home Designer Pro do not allow to add rooms on the attic so I add another floor with 1 foot high ceiling, but I don't know how to add the back dormer with the wall approximately 6 feet high in the back of the house as seen in the pictures I attached here. Please help!