If you are interested in courses for non-enrolled students, the Center for World Languages and Cultures occasionally offers courses. Visit the Center for World Languages and Cultures (https://liberalarts.du.edu/cwlc/learn-language/non-credit) or email them at cwlc@du.edu for help registering and general information about the language programs they offer.
You may also want to explore courses offered online through DU’s University College - https://universitycollege.du.edu/?gm-vt=1