Dear Fouzi,
do you mean, you need help for your application for university?
There is a place in Kassel called "Jugendmigrationsdienst" the adress is:
Königsplatz 57
34117 Kassel
Tel: 0561 / 57463720
You can call them and set up an apointment. I am sure they can tell you exactly what you need to do to start studing!
Best
Henriette