How can I find my half-brother?

I'm just 17, I have no job or credit card, so that means I can't afford to pay someone to find him. His name is Dustin, but due to my mother not wanting to talk about it and the most my dad knows is that hes about 22-24 and his moms name was Twanna (sp?) Collins from Indiana. I'm doing this on my own pretty much..But I have to just know. I want to maybe one day meet him and for him and my dad to talk.