Thank you for reaching out to the Wefugee Community!
I am not familiar with the language course landscape in Wesel but I am afraid that it will be quite difficult to find a official course taking place at weekends. Maybe you can manage to attend a class a few evenings during the week? I found, for example, this brochure from the VHS (Volkshochschule) in Wesel, which describes their course offers for the upcoming months. You can find contact details for getting information on evening courses on page 58.
I hope this helps and all the best,