Step 2 : create the wall (in a new body)

From this point on, we will assume that you have sufficient knowledge of the PartDesign and Sketcher WB to create a body and a new sketch in the XY plane.

After making the "SketchBase" master sketch visible,
create a carbon copy of this master sketch and adapt it to the wall drawing.

Create an extrusion with a length equal to

       <<SketchOpening>>.constraints.WallHeight

After creating a new sketch in the XZ plane and making visible
the master sketch "SketchOpening", create a carbon copy
of this master sketch, and adapt it to the design of the opening to be made.

Create a pocket across everything (on the right side!).