I understand that you want some guidance and you don’t really know where to start. A class run by a competent instructor does seems like the right way to get going. This is only true if it is provided in the right conditions.
I am wary of expectations towards novice group classes, as it can be a difficult setting to offer a favorable environment for dogs debut in harness. While a novice group format may provide a reassuring setting for the humans, it is more unlikely to be favorable for the dogs. If you decide to attend a group class, do so with the right expectations.
Setting your dogs for success is key. That is offering the best possible conditions to introduce them to the activity you hope to enjoy together. Here are my concerns and few key aspects to consider when you choose and decide to take a class.
Good conditions would be free of stress, stimulating, while not arousing. Good conditions shouldn’t push any dog over its thresholds, whether it is it’s attention span, exhaustion, stress. This is certainly achievable in a novice group setting but don’t expect it to be in that environment that your dog will develop and learn most. A group class should focus on teaching YOU how to evolve with your dog, with guidance for YOU to develop your dog. This means you can’t expect to take a class or multiple class and come out of it with an accomplished harness canine partner. Beyond the guidance you will receive, you will need to put in your own work in your own time in the best specific conditions for your dog.
Usually, novice groups will be constituted of a wide diversity of people and dogs. You may have individuals of all levels of fitness and divers levels of experience in dog training. You are likely to have dogs with a range of predisposed abilities and temperament, of which some don’t interact appropriately with each other.
Unfortunately, it can be difficult to cater uniform instruction to such group without risking to overwhelm some dogs and under-stimulate others.
Harness dog sports are also particular as they are physically demanding for the human as abilities will widely vary. In this regard, it is unlikely for the class setting to uniformly cater to everyone’s best physical abilities. Ideally a group class would take in consideration the humans fitness level and group accordingly.
In a group class, you may expect exercises to introduce your dog to harness work behaviors and such exercises can be helpful… but not all exercises are appropriate for all dogs; some may actually be counterproductive for certain dogs; and rushing through a series of group exercises will not provide positive training within a few short group sessions.
Your expectations should be for most exercises to be demonstrations for YOU to work on when your dog is READY and in an environment that provides good conditions for your particular dogs mindset. An excitable dog may need to work in a less stimulating and exciting environment, while a less driven dog may need a little more boosting energy to help him.
It takes time and commitment to develop a good harness dog and the learning is not linear. It is a mash of behavior that slowly come together. It’s over many outings in many different conditions, and getting to know your canine partner that you will find out what training it needs and apply the appropriate “tricks” in the appropriate setting. What will help your dog may not help or may be unnecessary for an other. Many of the good harness behaviors are transferable from day to day behaviors and can be reinforced in your daily routine much more effectively then with group exercises.
Set your expectations for a novice group class to be an introduction to the world of harness dog sports and to the work ahead of you. Don’t expect it to be a full recipe for the journey ahead.
Are there other options to start harness dog sports? For sure!!

You don’t need to take classes to get going! If harness sports intrigue you, and appropriate classes are not available: don’t wait! You can do this without formal instructions; on your own or with friends. It may be the opportunity to meet other dog crazy people.
Group outings are fun for dogs and a great way to get started. Your best bet is to join other experienced individuals or groups on their outings. Your dog will get to start surrounded by experience dogs. Experienced dogs know what’s coming up and they love it. Your dog will be surrounded by happy excitement rather than the confused stress of a group of novice.
The people accompanying you will have experience to share and without flooding you with a curriculum worth of information will provide the tricks as needed by you and your dog. You are likely to get much faster gratification and smoother progress.
You can’t find experienced adepts or clubs to get going with?
Honestly, you are still fine starting up on your own; you and your dog. Just give it a try. Join online groups, ask questions, exchange on the challenges specific to your dog and training conditions…. The interwebs is full of passionate people ready to answer your questions. The recommendations you get should all be in a sense that promotes a positive mindset and the welfare of your dog. Your dog can be motivated to work in harness, not forced.

You can educate yourself on the basic principles of harness dog sports through books, websites, forums. If you can find seminars or lectures providing theory instruction, I would highly recommend that. Any expert knowledge is an asset for your journey in harness dog sports. (But not worth putting your dog through the stress of an inappropriate group of inexperienced people and dogs)
If its not available, stop waiting for that practical class that you think will provide you the tools you need to get started. All you need to do is hit the trail with your dog and give it a try. From there, it’s all fun and games (with a touch of patience and commitment).
Have fun!