Without a recognized high school diploma, it is difficult to find work in Germany, or to directly start studying. If a graduation diploma is equivalent to a German diploma, is decided by an office called the “Zeugnisanerkennungsstelle” of the respective state.
General admission information can be found by country of origin and diploma on the following website:
To study you have apply directly at your desired university. If the foreign high school diploma does not allow direct university admission, the university will explain how to get to the needed diploma.
The “Studienkolleg” is a possibilty to study at a German university after another year of school, if the foreign diploma is only determined to be equvialent with a “Realschulabschluss”. Each state has a minimum of two “Studienkolleg”s with two different graduation diplomas. Depending on the diploma you can get addmission to a university, a business school, a technical university, or a college.
The courses in the Studienkolleg are tied to a subject. The university will tell you during application, depending on your desired field of study, ff you have to take a technical or humanities course. This means the Studienkolleg will grant you a “Fachabitur”, which means that before you start the course, you have to be sure what you are going to study. In the Studienkolleg you will receive 9 months of classes in the relevant subjects, write exams and at the end get a diploma.
If you graduate successfully, then you can apply again at your desired university with your foreign and your Studienkolleg diploma.
During the Studienkolleg you are also entitled to receive BAföG!
Further information can be found on the website of the “Studienkolleg”: