I had a son with another man almost 4 years ago. This man hasn't seen my son nor will he ever. He is a dangerous drug adict and I have a restraining order against him. Now I am married and my husband wants to adopt my son. The DNA father, we'll call him, is willing to sign over all parental rights. I don't want to go to court since he is willing. How do I do this? Where do I find the documents to do this?

You will have to go to court regardless, and you will need an attorney as in most states an attorney is required by law for an adoption. Most states require you to be married a year as well.

Start calling around and getting some free consultations with attorneys. See if any offer a flat fee for step parent adoption with a consent. If the bio father is willing to relinquish his rights then it's basically just paperwork and many attorneys will offer a flat fee.
I'm in Ohio, the flat fees I have found vary greatly. One attorney wanted $1,000 flat fee all up front and another wanted $550 flat fee and only $300 of that to start working. So you really need to talk with more than one attorney.
Turst me, I have been through this and figured I could do it all on my own and save tons of money. But when I called the courthouse they informed me, by law, I had to have an attorney for the adoption... and it really takes the headache out of everything because you know it is getting done right.

*Now keep in mind my info comes from my case in Ohio, you will get more specific answers when you visit an attorney in your area*

Once you hire an attorney, they will draft up a relinquishment of rights form and send it to the bio father. The bio father will need to sign it and have it notarized and send it back to your attorney. After this is done, the bio father doesn't have to appear in court. Then your attorney will focus on your husband. He will need to have a criminal background check done, fingerprinted, get a physical etc. You will need to get personal referenences. A home visit will have to be preformed in which you, your husband, and your child will be asked series of questions. After everything checks out a court date will be set. Your child will have to appear in court too. You can include a name change as part of the case as well, if you are wanting to have your child's last name legally changed to your husbands. Once everything is finalized in court and new birth certificate will be issued with your husbands name listed as the father. Your ex will no longer have any legal claim to the child. No child support will be paid on his behalf. The child is lawfully, in everyway, your husbands child now.

Again, I am in Ohio, so things may very slightly where you live. But you need to call around and get some free consultations with attorneys. Get the specific order of things where you live, and find out fees.

Good luck.