character controller

How can I move a character up as in the y axis ?

The above answer will cause your player to pas through objects, because it does not do physics calculations.

If you know your using a character controller, so the next thing you should do is look at the subclasses for the CharacterController class.

Making a player jump is a fairly common operation so example code is in the scripting reference:

In this case the "Move" function exists in the character controller class.

http://unity3d.com/support/documentation/ScriptReference/CharacterController.Move.html

if u r using the character controller u may implement this

var speed : float = 6.0;

private var moveDirection : Vector3 = Vector3.zero;

function FixedUpdate() {
var controller : CharacterController = GetComponent(CharacterController);

    moveDirection = Vector3(0.0, Input.GetAxis("Vertical") ,0.0 );
    moveDirection = transform.TransformDirection(moveDirection);
    moveDirection *= speed;

controller.Move(moveDirection * Time.deltaTime);

}

to continually move up would be

function Update()
{
 transform.Translate(Vector3.up * Time.deltaTime * 100);
}

but to go up once, that would be different, do you mean as in jumping?