How do I serve someone with a subpoena?

I'm involved in a civil lawsuit with a body shop for improper repairs to my vehicle. I already spoke to the arbitrator on the original court date who told me that in order to win my case I really should bring the mechanic in with me. The mechanic works for Land Rover and they have some stupid policy about allowing their mechanics to testify in court. The manager said I need to serve the mechanic with a subpoena. What EXACTLY do I need to do to serve him with one? Thanks...