I had a baby in Florida I moved to Washington when he turned 10 mnth the babies father has not been involved since I got pregnant he left when he found out I was having his baby he doesn't pay child support or visit or calls I don't know where he is now. My fiancée wants to adopt my son but we don't know how to go threw the process?

No that's not considered abandonment. You will have to make a good faith effort to locate him and show the courts that you did so. Hire a Family law attorney who can advise you what you need to do and prepare the paperwork.

By the way, if you did not file for child support, then he doesn't owe any.