It used to be that Green Screen technology was extremely picky, and the background and lighting had to be very precise for the effect to work. With Zoom’s implementation, this is not true: “Virtual Background” is very forgiving of inconsistent backgrounds and lighting. This makes setting this up and playing with it comparatively easy.
If you have an odd-colored, solid wall you can use as a background, go ahead and try that as a background. If you have a strongly-colored bedsheet, try push-pinning that to the wall to see what works. Or search Amazon or elsewhere for “Green Screen Backdrop”. You will see many for over $100; you don’t need these. Mine is 5 by 6 feet, and cost $8. It is light enough that I can hang it by 3 small sticky-back velcro tabs: one side stuck to the painted wall, and the other side stapled to the green screen:
The reason that a bright green is recommended is that this is a color that doesn’t show up often in clothing. You can also buy Blue Screens that are similarly bright and unusual for a clothing color. If you do wear clothing (or glasses, or have anything else) that is too close to the background color, it will function like a Harry Potter Invisibility Cloak: