As a US citizen, you'll need to work with an adoption agency and obtain approval from US Citizenship and Immigration Services (USCIS) before proceeding with the adoption.

You'll also need to comply with the Hague Adoption Convention, an international treaty that regulates intercountry adoptions, and obtain an immigrant visa for the child.

I recommend consulting with an immigration attorney for professional guidance on how to proceed with the adoption process and acquisition of a visa for the child