Can my husband adopt my daughter? Her father is in prison and will be until after she turns 18. I have been with my husband for 5yrs, we have two other children together and my daughter calls him dad. What would I file for him to adopt her?

This question has been often asked (and answered) here.

Since an adoption is a legal process, you would be well served by getting an attorney to draw up the paperwork. The attorney will make sure you do all that you need to, getting the father's rights terminated, filing the petition etc.

So your first step is to start interviewing attorneys