I really want to change my daughters last name, but, I don't know where to start.?

When I had my daughter, who is now 2, I was married. 3 months after Mya was born, he left the country and went to Argentina where he now lives. We divorced a few months after he left, and I changed my last name back to my maiden name. My daughter still has his last name, and I really want her to have mine. Does anyone know how this process works? Where should I start with this?