how can i make my character jump?

Try transform.position += transform.up jumpSpeed Time.deltaTime;

That should do it but you need a variable called jumpSpeed and you need gravity on your player or he'll stay in the air.

Characters jump up and down along the y-axis.

So, all you ned to do is write a short script in your Update() method so that you can detect the button pressed and then translate that into a movement along the y-axis.

Here's a snippet.

 > function Update () {
 >         if (Input.GetKeyDown ("space")){
 >                 transform.Translate(Vector3.up * 260 * Time.deltaTime, Space.World);
 >         } 
 >} 

Another simple technique is to use an animation controller. Set the transition from walking animation to a jumping animation with a simple bool variable and then your character will play a different animation whenever you toggle the bool value.

Here's a snippet.

 > function Update () {
 >         if (Input.GetKeyDown ("space")){
 >                 myAnimator.SetBool("letsJump", true );
 >         } 
 >} 

To lock the mouse just use Cursor.visible = false; in your void Start.

Simple as that :)

     #pragma strict
    
     public var jumpHeight : int = 10;
     var inAir : boolean = false;
     
     function Update () {
         if (Input.GetAxis ("Jump") && inAir == false) {
             GetComponent.<Rigidbody>().velocity.y = jumpHeight;
             inAir = true;
         }
     }
     
     function OnCollisionEnter () {
         inAir = false;
     }

The inAir variable will ensure you don't multi-jump.

Add "FPSWalker" script in standard assets to your character.