You can also use the Armory to find good talent builds from top players.

Once a character achieves tenth level, it will begin earning talent points at the rate of one per level. Talent points can then be spent at the Talents window. Every class has three lines of talents, not including a character's racial talents list. Talent points can be spent to purchase talents, which can do a variety of things. Many talents can improve your class' existing abilities, give you new abilities, or improve your class skills. All classes have the same talent options, but no single character can hope to acquire every single talent. Thus, there are many talent choices open to your character, and your choices will help differentiate you from other players playing the same class.
Choosing Talents
very class has three categories of talents that are organized by your class abilities. Mages, for instance, rely primarily on their spells, which are broken up into the arcane, frost, and fire schools. Thus, the mage's talent categories are arcane, frost, and fire. Each category can be accessed using the tabs at the bottom of the Talents window. Talents are bought on a one-to-one ratio. One talent point spent on a talent gives you one rank in a talent. You do not accrue talent points until you have advanced past the first few levels of gameplay.
The talent system is tiered. There are low-level talents you must buy and master before you can learn high-level talents. However, you can see all talents in a category, and see the paths leading to all talents. In addition, mousing over any talent tells you what the talent does and what requirements you must meet to learn it. Talents that are grayed out cannot be learned, either because you have no talent points to spend or because you do not have enough mastery of other talents. Talents do not have level limits.
Learning Talents
o learn a talent, mouse over the talent first and decide if it is right for you. Talents are difficult to unlearn, so you should be sure before you commit to one. You can visit a class trainer to unlearn your talents. It will cost money to unlearn your talents in an increasing amount until it reaches a high cap. This is to prevent players from changing their talents daily and devaluing the choices that must be made. Also keep in mind that you cannot learn every single talent, so you should make a choice about which talents or what category of talents you want to learn. When you decide on a talent, left-click on it to learn it. There is no confirmation of your pick. Once you click on it, you buy it. If by purchasing the talent you open new avenues of talents, the newly unlocked talents will turn from gray to bright. All classes have talents that allow the player to customize their character. Talents can be applied in the following ways:
To improve a class' existing spells or abilities. To alter the functionality of existing class spells or abilities. To acquire new spells and abilities. To improve class skills. The three lines of class talents are geared towards each class' main strengths. For example, mages naturally divide their talents into arcane, frost, and fire, which mimic the three main schools of magic mages learn. Warriors have the talent lines of arms, fury, and protection. Each category of talents is designed like a tree, with new talents branching out from a core set of base talents you can learn at low levels. Within each tree, a character can learn talents that make that character more effective in all the abilities and capabilities that fall under the heading of that talent tree. The frost line of talents, for example, enhances a mage's proficiency with frost spells. The warrior's protection talents improve the warrior's taunt and defensive abilities. No player can ever hope to become a master of all three lines of talents. In fact, with dozens of talents per line, and multiple ranks to each talent, the most a character could hope to fully master is one talent tree, and a little of another one. Talents can be seen by clicking on the Talents button or pressing the hotkey N. Mouse over each talent to receive a description of what it is and how to use it. Be sure to peruse your class' entire array of talents before choosing them. It helps to have a goal or general theme for your character when purchasing talents, rather than picking them haphazardly. Of course, there is nothing wrong with experimentation, but you may find it wise to research all your class' talents before purchasing them. The talent calculators are provided so that you can plan out your points prior to spending them. You can also use the Armory to find good talent builds from top players.