1. Register to local authority (Gemainde)
There I will tell them that starting on my arrival day, I am officially stay in Adrian´s house.
2. Register to Indonesian Embassy or Consulate
Its important, because when something bad happen they can help you and also for election (Pemilu). I stay in Hannover, I dont need to go to KBRI Berlin but KJRI Hamburg which is not really far away from my home.
3. Register to foreign authority (Ausländerbehörde)
After you register your self there, you will get your residence permit (Aufenthaltstitel). It will be your ID card in Germany.
4. Make health insurance
Everything is expensive in Germany, so make sure you have health insurance.
If you have any question, feel free to ask me.