All New Users are soon faced with the Necessity to Set a Custom Illustrator Background Color and when they try to looking for a Solution they Start to Look into Menus and Panels without to find anything Related to Background. After googling around may be they find the Adobe Documentation about how to make a Paper Simulated Colored Background. But if you try make your changes like that after a while when trying to Fill or Stroke with Whitish you will find that it isn’t a definitive Solution because you Can’t clearly Perceive Whitish Fills and Strokes Neither on Paper Simulated Background.
So while waiting for an new Illustrator Functionality to come the only one Actual Solution is of Making a Truly Simulated Background where you can Clearly Perceive also White Strokes and Fills:
Window > Layers
Create a New Layer and Place it Below all others
On the Layers Panel Click to Select the New Layer
Select the Rectangle Tool
Set the Rectangle-Background’s Color
Draw a Rectangle larger than your Document size
Lock your New Layer so it will not Interfere with your Work
Now you are Free to Stroke and Fill also with Whitish Colors ;)