Admission Doctoral Studies
For doctoral students, the application procedure is usually split in two parts: the formal part where you have to present certificates showing that you are qualified to start with the doctoral program, e.g. an acknowledged master's diploma, and a part where you have to find a supervisor accepting you as a doctoral student.
As often, you will be employed to do very specific research, e.g. as part of a bigger project, or depending on your language skills, as a teaching assistant, you will have to write an application letter and a CV to the professor offering the position. There are other ways of financing your stay here, but especially then you will have to find a supervisor willing to apply for additional funding with you.