Hi Mariso,

If you are using AutoCAD for Mac, than "Display paper background" not available in application options, unfortunately.

Could you post screenshot of what you see when you switch to Layout? By default you should see blank "page" with viewport to Model space which created automatically.
If you need to change background colors in Layout - it is possible in AutoCAD for Mac, but for further instructions I need to know: which version of AutoCAD do you have (full or LT)?

Maxim