Good place to start…find out where your going to end up.
Once you determine who will be airing this TV spot,(local cable company, local broadcast station, regional or national) you will have to ask how to deliver it to them. BetaSP or Digi-Beta are a couple of examples.
You may already own the equipment necesary to complete this delivery or you could rent.
It also may be a good idea to hire someone to transfer your work to one of these delivery methods. This person could surely give you more specific answers as to how to deliver it.