Instructions
Visit a stable master and stable your pet if you only have Call Pet 1 or if all of your Call Pet slots are full. Stable masters appear in most large towns and in all major cities. If you have Call Pet 2 or higher and have an empty Call Pet slot, you can click the "Dismiss Pet" spell instead of visiting the stable master.
Find a cat. Cats roam around in the majority of zones in the game. Most of them vary in appearance. After you've found the desired cat, walk within 30 yards of it and click the "Tame Beast" spell. The cat will begin to run toward you, and hearts will float above your head.
Stand still. If you move, the spell will cancel. A channeling bar will appear on your screen during the taming process. It indicates when the cat will be tamed. Once the cat is tamed, you can rename it by right-clicking its portrait.