Dog training is when your mistress or master treats you like a dog, training you to behave like one and follow commands such as "sit", "stay", or "come". You become their pet and will thrive on being patted on the head or called a "good dog". You might be expected to behave like a dog would, walking on all fours and barking instead of talking, and kept in a cage if you do not do as told. You may be treated poorly as you are not worthy as a human, and so will be humiliated and disrespected. However. This is a slave-dog and not necessarily going to happen, so explain to your mistress what you are looking for before you go.
One of the most essential parts in becoming a dog is the outfit. Many may choose to wear knee pads or padded gloves so that, when they are crawling, their knees are protected and they will be able to retain their dog-persona for longer. They will also wear a mask to make it look like they have dog-ears and a dog-nose. Collars and a lead are essential pieces of kit, as your master will pull you along by it and it shows to others (for those wanting some public humiliation) that you have an owner.
Your mistress or master might provide you with a bed to sleep on, or they might expect you to simply nap on the floor. They may even expect you to become a dog in terms of your personality, but this will depend on what you are looking for. For some, it is simply dressing up as a dog and acting like a pup, while others may want to be treated poorly as they are not good enough to be called "human". Let your partner know exactly what you are hoping for so that they can provide you with the best experience.
Remember to use your safe word if it gets too much. It will help your partner understand your limits and also allow you the chance to take a break, should you need it. Being a dog for a long period of time can be exhausting, so breaks can be useful.