changing my son's name

i am trying to change my son's name. we have been living in illinois for the past 6 months. i have full custody of my son as i have had since his birth. my question to you is this: what must be done in order to change his name and about how much would be reasonable for a fee? i also would like any advice you can give as to what i can do to make this process as smooth and quick as possible. thank you.

The court will want the Bio-fathers permission, if he will give it you don't have a problem.