Would appreciate help on how to attach this wall to the roof.
I believe you need to draw the same wall (as a separate wall) behind these back to the roof line at the top of the wall, then make the height of the wall what you need as a height, and set the elevation of the bottom of this wall at the height you need.(probably need to turn off cleanup).
Then edit the 2 new walls and select "rake bottom of wall to roof"
Thanks for the help.