Your character's Alignment is the moral and personal attitude of a character, be they god or mortal. They are not ridgid and can be interpreted in many different ways, but are good guidelines for deciding how a character will act for a given situation.
The nine alignments are: Lawful Good, Neutral Good, Chaotic Good, Lawful Neutral, True Neutral, Chaotic Neutral, Lawful Evil, Neutral Evil, or Chaotic Evil.
Order vs. Chaos
Characters that are lawful generally support authority, rules, and reliability. They usually believe that the world works best when it is orderly, and that laws are a way of achieving this order. Lawful characters do not necessarily fallow legal laws, but rather their own personal code. However they do not want to cause unnecessary chaos and will try to work around set rules, only directly challenging them if they don't feel they have another option.
Chaotic characters generally revel their personal freedom, and often see laws as obstacles that impede their lives. They see the world as chaotic, and that it is a folly to try to control it through rules. Chaotic characters do not always view laws as unjust, but will break them as they see fit. They may have a personal code, but one that will change as they see fit.
Good vs. Evil
Good characters value the life and well-being of others and go out of their way to care for them. They often make personal sacrifices to ensure the safety of others. They rarely go out of their way to harm others, especially for a selfish reason.
Evil characters often have little to no compassion for others, and would harm them for personal gain. Some of them hurt others because they are sadistic, want to gain something from the action. Many of them know that their actions are evil, but some twisted worldview and don't believe that they are doing is wrong.
It is a misconception that neutral characters are unable to make up their mind or do not feel strongly about their views. Someone who is neutral on the Law-Order axis could have strong feelings about not becoming too strict and too lax for example, and someone who is neutral on the good-evil axis may strong oppose taking the lives of innocents, but wouldn't go out of their way to help people in need.