I'm sure you understand that finding your biological father is not going to be possible with only a first name.
You might try talking to you mother. Surely she has more information than that. If you have already talked to her and she does not want to share any information with you, then maybe there is a good reason that she would prefer you not know who he is.
I take it that your biological father has never been a part of your life. That being the case, why the desire to find him? Have you considered that maybe he does not want to be found? What is the value to you of finding him?
In any case, unless you have more than a first name, you will not find your biological father.