Since you posted in the show ring section I assume that is what you are interested in?
I feel like maybe you are confused as to what to get the dog into.... As a starter, there are a few different venues that Dobermans seem to do well in. Most of the time, people stick to one particular venue, or one venue very seriously, and another venue 'for fun'.
The main 'venues' I would look into learning more about would be: agility, obedience, rally (like obedience but a little more 'relaxed' atmosphere), conformation (show ring; typically AKC conformation for Dobermans is extremely competitive and you need a dog who was specifically bred from proven parents to be successful), and schutzhund. Schutzhund is a dog sport divided into three phases 1. Obedience 2. Tracking and 3. Protection. For schutzhund, most dogs can compete and do well in the obedience and tracking portions with a good trainer, but the protection aspect requires certain genetics (proven parents) and a certain upbringing to be successful. Your boy (I think?) is still young, and depending on his natural drives, you may be able to still do the protection with the right drive building, training, etc but it is most likely a stretch.
Heeling is important for most training, but it sounds like you are interested in competing in either AKC Obedience, Rally, or possibly Sch obedience. Heeling is crucial in all 3 venues, so it is honestly up to you as to what you want to pursue.
It may help us guide you in the right direction depending on which breeder your dog came from to see what he is bred for. If you pick a venue you are interested in, most of us can help guide you towards a good trainer or training group to learn more about. Good luck with your dog!