Firstly look what you pet wants as food here. Then just rightclick your pet while holding the food item in your hand. It will first increase the saturation of your pet your pet and when it is at 100 saturation it will heal it. Every food item has a saturation of 6points and every missing saturation and HP will use 1 point.
Is there a way to have more than 1 pet?
No. You can only have one active pet at the same time. However you can store pets and switch between them (NPC or command).
Why can't the pets on my server attack anything?
Your pets just don't have a damage skill (Damage or Ranged). Select a skilltree with a damage skill or add a damage skill to your existing skilltrees.
Why can't I tame the Enderdragon/Wither?
ProtocolLib is required for the Enderdragon to be tame-able.
The leash requirements for the enderdragon/wither are set to impossible by default. Change it to one of the other requirements (or replace them with an empty list ) in the pet-config.yml.
Why doesn't the Enderdragon/Bat/Phantom etc; fly?
There is no Flying AI in Minecraft.
Pets utilize the Tamed Wolf AI once they are tamed as a MyPet.
Can I make my Pet Sit/Stay?
Yes, you can make your pet stay by Shift + Right Click
All pets can be told to Stay, not just the standard tame-able mobs such as Cats and Wolves.