Combat is an important part of adventuring in Allods Online. You will be required to kill many NPCs throughout your travels, and sometimes even other players. Depending on your class, you may also be required to heal friendly players.
To attack an NPC or player, or to heal a friendly player, you must first target them by clicking on them. You may also select them by pressing "TAB" which will target the nearest NPC or player. You must also be within the defined range of your spells and abilities before you can use them. You can find this information by moving your mouse over a spell on your action bar.
If you attempt to use a spell on a target that is out of your range, you will receive a notification message that says you are not close enough. Simply move closer to the target until you can successfully cast your spell. There is no auto attack, so be prepared to start using your spells the minute you are in range.