For the time being Riley I think this is well out of your reach.
Do you have any experience with hardware and/or software?
I've been around a while and I can't think of how to do this off the top of my head, except to interface with someone's web site that already tracks their balloon, and you don't need an Arduino for that.
As for tracking any old balloon I assume they transmit GPS coordinates so you'd have to know what frequency they use and tap into that. This is not a flashing LED project.
Rob