This question has been answered by BobRay. See the first response.
I am brand new to modx ... (Drupal user foe ...)
Yes, that is what I figured. I just saw a mentioning of the sample site in a review, and thought it would help me get started a little faster.
I hate to say it, but I think in your situation, I would start over -- empty all the DB tables (leave the DB itself), delete all the files, then download (or unzip) the files and run setup again.