How to make a button script.

I'm using Unity 4.6, and and very new to Unity.

So I created a UI in the editor, and now I want to add some functionality to the buttons in that UI. I've created a C# script and attached it to the relevant button object, but I'm not sure how to call a specific C# function when the button is clicked.

I've done some googling, and decided that OnGUI was the way to go... But using OnGUI triggers even if I click nowhere near the attached button.

I've done some more googling, and decided that what I want is to implement OnMouseUpAsButton, but now nothing seems to happen when I click the button.

Here is my code, if you're interested. using UnityEngine; using System.Collections;

 public class btnPlay : MonoBehaviour {
 
     private float startTime = 0.0f;
     private float animDuration = 0.5f;
     private bool animated = false;
     private float startAngle = 0.0f;
     private float endAngle = Mathf.PI / 4;
     private float Z = 0;
     private float M = 0;
 
     // Use this for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         if (animated) {
             float currentTime = Time.realtimeSinceStartup;
             if (currentTime - startTime > animDuration) {
                 Camera.main.transform.position = new Vector3(M * Mathf.Cos(endAngle), M * Mathf.Sin(endAngle), Z);
                 animated = false;
             }
             // Transform
             float dt = (currentTime - startTime) / animDuration;
             float theta = (endAngle - startAngle) * dt + startAngle;
             Camera.main.transform.position = new Vector3(M * Mathf.Cos(theta), M * Mathf.Sin(theta), Z);
         }
     }
 
     void OnMouseUpAsButton () {
         startAngle = Mathf.Atan2(Camera.main.transform.position.y, Camera.main.transform.position.x);
         Z = Camera.main.transform.position.z;
         M = Mathf.Sqrt(Mathf.Pow(Camera.main.transform.position.x, 2) + Mathf.Pow(Camera.main.transform.position.y, 2));
         startTime = Time.realtimeSinceStartup;
         animated = true;
     }
 }

Any help would be very appreciated.