Ausbildung as Non-EU country

Hello,
i am from Bosnia and Herzegovina and i just finished the Middle School. As i got family members in Germany i am interested in moving there thru a Ausbildung. So i want to know what  documents do i require to move there as an Non-EU Citizen.
The Advantage ist that i got family members with an Apartment so i can get as i heard something like an Check in the Appartement papers that i got a place to stay. And something like a gurantee Letter that they will Finance my so i dont need the 9000€
Any information would Help me.

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