Adoption in HK

We are seriously considering adopting a child in HK. Has anyone gone through this procedure? As we are a mix couple, it would be great if we could find a mix baby, however this is not a major concern. Does anyone know where we can go, how long it'll take and what are the costs involved. Do they let you choose the sex of the baby? We are a loving couple and already have a wonderful son, however after years of trying we haven't been successful in adding to our family. So we thought we might adopt a child.