Hi:
You need to request non-identifying information about the biological birth parents and make arrangements to work with an OK confidential intermediary to help you obtain more information. You can read about how to do this using this website and doing a search on "Oklahoma" and reading all the info pertaining to that state:
https://www.childwelfare.gov/pubPDFs/infoaccessap.pdfBest of luck to you!
Terri