I live in Missouri with my wife and our (her) son and we have been talking about me adopting him and have been told about running an add the bio fathers local paper stating that I was willing to adopt his "son" and what county I would do it in and if he did not respond in 30 days then I could go ahead with the adoption is this true

No, not exactly.

You have to follow proper search procedures for the father of the child and if found ( or if you know where he is) he is served with legal papers, first asking him to sign his rights over to allow the adoption. If he will not sign, he is served notice of the court hearing on this.

If he can not be found, after following all the rules of the court, a notice is placed in a specific legal newspaper, this would serve as legal notice.

If you can not locate him, the process is much harder and will cost a lot more money than if he is found.

You need an attorney. Before a court will allow an adoption, they will require that the bio father be contacted and agree to the adoption. If the bio father's whereabouts is unknown, they will require that a good faith effort be made to contact him. What this good faith effort involves will vary according to the court. A legal notices ad is a possibility.

This is why you NEED an attorney. A local attorney will prepare the adoption petition properly, making sure everything is done according to the local law and courts.