If I want to draw on a black background with bright neon colored pens and brushes (sort of a Khan Academy look), how do I do this in Krita?

Start with creating an image with a black background, and then whatever colors you select in the color selector.

Does creating an image mean importing an image into Krita? (I should have clarified that I am new to Krita.)

For example, MyPaint has an option for changing the canvas color from white to another color. I thought Krita might have a similar option, but apparently not. If I understand your comment, I need to create an all-black image (using Krita or another program), and then import that image into Krita and draw on it?

In the new image dialog, open the content tab and select a different background color.

Thank you! That's just what I needed.