have a 1985 190E Mercedes. I need to replace the alternator and do not know how

now in your question,you have 2 different years posted.1985 and 1990.here is a link for a 1991,maybe same as yours.copy and paste link. Changing a 1991 mercedes 190e alternator and belt - YouTube 3:55 www.youtube.com/watch?v=VVoSED9rExk