Wayne,
Create a Display Cube in the Cabinet/Assembly Editor. The width of the cube is the width of your round wall (or a little more if you want)
The length of the wall is the radius of your round wall plus some extra.
The Depth is the height of your round wall. The texture can be anything as it can be changed in the room.
Take this cube to the Contour Editor.
Click the circle tool and choose Three Point Arc.
Create an Arc that matches the outside diameter of your round wall.
Click on the Copy/Move tool and select Move and enter a value equal to the thickness of your wall and click OK.
Click on the arc you created then move the cursor toward the inside of that arc and click again. You should now have another arc inside the first.
Select the line tool and draw lines from both arcs like this
Exit the Contour Editor then right click and choose Cut Pocket using Closed Contour.
Click on one of the contours and it will turn green.
Click the next button and select Cut Through and then OK
Repeat for the other Contour.
You should now have your wall.
Click return and choose to save the changes when prompted.
This wall can now be saved as an Assembly to use or you can export it to the display parts editor to make the textures work better and save it as a Display Part.
This is placed in a room just like an assembly or display part. To make the S curve simply place two of these walls and rotate on opposite the other.
Kerry