Simple way to validate a check box using keyword tests.

I've tried browsing through the community posts and I can't seem to find a simple explanation on how to do the following using keyword tests.

If a checkbox is checked then do something, else if its unchecked do something else.

I've attempted using "if ... then" and have had no luck and I have tried using the "checkpoint wizard" also, would anyone happen to have a simple example they could provide?

Thank you in advance.