So I already read that tutorial but I can't manage to follow this line :
"Open a new file and create a simple inclined wall, with an angle approximately equal to the sloping ceiling one. "
How can I create a simple inclined wall ? When I try to create a wall there's no option to incline it .

Hello,

I'm trying to create a room which look like this :

http://www.noelshack.com/2017-02-148398 ... g-0779.jpg

How could I do it ?
Especially the inclined wall?

Thanks