If I have full custody of my child and his biodad does not ever have contact with him and my husband my child's stepdad wants to get his name changed to ours.. what do I need to do?

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

But I have to ask why you think your situation was different then the other poster and why my answer wasn't enough.

You have to petition the court for a name change and that means getting the father's permission or show a good faith effort to do so.