Dear Salah,
Welcome to the Wefugees Community and thank you for reaching out to us.
First of all, it is not clear to me if you are already in Germany or if you are still in your country of origin and looking for options to move to Germany. If the latter is the case, I can recommend to get a first overview on the different visa types and procedures at "Make it in Germany".
Regarding the adoption, the German law (§1767 Bürgerliches Gesetzbuch/BGB) says:
"An adult may be adopted as a child if the adoption is morally justified; This is particularly to be assumed if a parent-child relationship has already been established between the adopter and the adoptee".
Why do you want to be adopted or what do you expect from it? I found a useful website (it is in German but you may use the translate function) which provides information on this topic.
I hope this helps and please don't hesitate to get back to us to explain about your situation in more detail or if you have any further questions.
All the best,
Meike