Select Controls from the Setup menu to configure your keyboard and mouse (and joystick) for the current player. Selecting one of these input devices lists each action in the game, and what control activates it for that device. You can remove controls from actions, and add them by pressing the control you want to use for them (these can also be added to Mouse Button 4). Select Ok to save any changes, or Cancel without saving. If you change your mind, select Restore Defaults.
These are the default controls for keyboard and mouse.