Student job in Siegen

The "Experts" title on this forum is only used for people who have an eye on the forums and report misbehaviour.
I doubt that any of us "Experts" can give you a job.
This site has a classifieds section with (very few) job ads, which you may want to look into, but your main focus should be on other avenues like online job portals and notice boards in and around your university.
If you are non-EU-citizen on a student visa, you must also first check if and how much you are allowed to work. In most cases, students can only work a limited number of hours in jobs related to their stiudies (e.g. internship or trainee positions) - you cannot earn your living expenses that way!

I hope you've settled in at the university. Look up  jobvermittlung on the university website for job offers and related information. The following   Facebook groups might be helpful
-International Students in Siegen
-English Speakers in Siegen-Wittgenstein
-Neu in Siegen
All the best !