How do I create a ceiling on the underside of these stairs?

[lnicholson676970]

Im very new to revit, I have created this winder stair by sketch in place.
I created the balustrade using a wall component and editing the profile. Was there a better way to create a continuous balustrade?
How do I create a 'ceiling' to the underside of the stair? I want to enclose the stair so to speak.
The ceiling would have to be some kind of double curve to accommodate the fact there is no flat landing where the stair changes direction.

Thanks.