How to bond someone out of jail?

My dad who does everything by the book, never speeds and is a old nice man apparently had a warrant. They took him to jail before he was about to board a flight to see his sick brother. I feel really bad because he was so confused. But I remember he got in trouble at the company he worked for but since that had quit. The cop said it’s a misdemeanor and I can bail him out for $100 tomorrow. How do I do this? What should I know? Please help! He is old and diabetic.