Hello Mayar, this information might be useful in your circumstances:
- If you've been recognized as a refugee in Germany, you can file a request for family reunification with the immigrant authority ("Ausländerbehörde") within in the first three months after having been recognized as such.
- Your child should apply in the German Embassy or Consulate in your home country for a residence title for the purpose of family reunification for Germany.
- When the child has arrived in Germany, register him as your family member with the residence registration office and with the competent immigrant authority (Ausländerbehörde). In order to do so, you need to collect the passport, birth certificate, tax certificates as well as evidence of tenancy and possibly other documents, depending on your specific family circumstances.
Hope it helps :)