The Tracking Number is assigned by Groundspeak, where you purchase a unique six-digits of letters and numbers from Groundspeak's database, and that's what gets imprinted on the coin (and the coin's design must be approved in advance). You can't use just any number as an Official Groundspeak Tracking Number, and you can't even choose the number from their list. But you can get a custom prefix when ordering 1000 custom coins:
http://support.Groundspeak.com/index.php?pg=kb.page&id=332
If your coin has six digits inscribed (typically laser-engraved), and certainly if the coin says something about "Track at (Groundspeak.com or geocaching.com)", you can track it here: https://www.geocaching.com/track/
Submit the number, and the page may give more info about the item, even if it is not activated.
The "Activation Code" comes with a Geocoin's packaging when you buy it. If you wish to activate it and don't have the Activation Code, try this: https://www.geocaching.com/track/activate.aspx
If you think you've found an actual Geocoin and can't figure out the Tracking Number, contact Geocaching.com:
http://support.Groundspeak.com/index.php?pg=request
It's no good to post the numbers in the Forum, since a Tracking Number is supposed to be kept secret.
If you have a coin that you wish to travel, but it is not a Geocoin, one inexpensive option is to buy and use the number from a Travel Bug Dogtag, or better yet, attach the tag somehow. But if the coin already has other numbers, prepare for mass confusion.
If you don't need "Official Tracking", you can place most any item in a cache, with info and a request that people contact you when they find it, and see how it goes.
I apologize. I read the FAQ on the topic. Thought I said that. Sorry. So basically what I am reading in your reply is that one must buy a trackable before it can be activated and tracked. Am I correct? In the FAQ one of the vendors was a military challenge coin website. I have one with a serial number on it already. I'm just looking to activate it and have it tracked. I am asking how to activate it. Where does the activation number come from? Those questions were not answered in the FAQ