How can I find my biological mother

Hire a private detective, contact the adoption agency, ask your adoptive parents.

It depends. Was it a closed adoption? If so, it won't be easy.

How old are you? How long ago was your adoption?

If you have your adoption records then you can look on there, and get enough information to find your biological mother. Your adoptive parents should have a copy that they might be willing to let you look at. But like the answer above, was your adoption open or closed? Mine was open, so it was rather easy to find my birth mother.

Please do not give advice on the adoption boards until we have a general idea of how old the original poster is.

It is illegal to help a minor search.