je n'ai pas pu demarrer le premier cours de pronociation de l'alphabet de la langue Allemande

I can't get the difference between ö and ü in pronunciation. Can anybody help? Thanks in advance.

Hi, anyone taking this course too??

is there any test after topic and why i cant find it and one more thing why i dont get the green mark next to the topics that i read thanks

Yes. It would be better if there were tests too. Thanks