How can I find out who my father is?

Hi i am writing to find out if i could get a DNA test done my mum has told me briefly what happened which is my possible father is my father but he is uncertain about this because there was a miss understanding at the time.

I was just wondering how i go about getting him to take part in the dna test so i know who my father is thank-you.

If you could get back to me that would be great.