Unity how to change text mesh when pushing button

Let say you want to change the value of text mesh by 10 everytime you pressing a button,

below is what you should do

1. Open Unity, add text mesh let say "myText"
2. Create a new javascript and attach it to your button
3. On your javascript put

private var myCredit : int=100;

private var myTextMesh :TextMesh; 

function awake()

{

      myTextMesh=transform.Find("myText").GetComponent(TextMesh);

}

function OnMouseDown()  //when pressing button

{

      myCredit += 10; 

      myTextMesh.text =myCredit.ToString();

}