I really don't want to hurt your feelings but red lights started flashing immediately. A first horse is NOTHING like lesson horses or lease horses. And a colt (I'm hoping he's gelded?) is not a good decision. Especially since you're asking people online how to go about halter breaking and trailering him... Those are things you need to know before even thinking about working with a young horse, let alone buying one as your first horse.
I bought my first horse after riding for 9 years. She was super sweet and easy the first few months until she gained her weight back (she was neglected). Then she was seriously dangerous, mind you I had worked with problem horses before. It took a good year and a half before we even started to like each other. Point being, I shouldn't have bought her as my first horse. Do I regret it? Absolutely not. Do I love her? Irrevocably. But I would have also loved a safe, older horse.
Honestly, I wouldn't want you to buy this colt (he's not a foal) even if you do have a trainer. Buy a "made" horse to enjoy as your first, and then in 5 years if you still want a young horse, go for it.
c'est la vie