Show what you have so far that is producing a result. Are you trying to do City Engine stuff in arcscene?
no! I wish to build my house in arcscene .....and i have troubles with the roof
Displaying 3D multipatch features—Help | ArcGIS for Desktop
would be the place to start... note, that near the topic of the help is a little toggle that will allow you to switch between arcmap versions... which should reflect changes between them.