Error CS1519 Help

I want to call this code:

CBBinding.showInterstitial(null); 

Into here:

using UnityEngine;
using System.Collections;
using Chartboost;

public class Menu2 : MonoBehaviour {

	CBBinding.showInterstitial(null); //error
		private Ray ray;
		private RaycastHit rayCastHit;
		
		void Update ()
		{
			if(Input.GetMouseButtonDown(0))
			{
				ray = Camera.main.ScreenPointToRay(Input.mousePosition);
				
				if(Physics.Raycast(ray, out rayCastHit))
				{
					if (rayCastHit.transform.name == "PlayButton")
					{
						Application.LoadLevel("Main Game");
					}
				}
			}
		}

	}

But i keep getting that error saying “unexpected symbol ‘(’ in class,strut, or interface” If you can help thank you

You cannot call code outside of a method.

If you want to call that code once, put it in a Start() method.
Otherwise put it in your Update() method.