How do I change text from Black on white to white on black?

[Joe G.]

I also would to add a 5 cell bar starting white and gradually changing to
black.

 

[Luke M]

For future note, put your question in body, as subject line gets truncated.

Format->cells, change font to white color, pattern to black

As for a gradual change, you could try formatting each cell progressively
less and less black. Say, 100%, 80%, 60%, 40%,etc. You can use custom colors
to get the exact level you want.