How to write a script which will switch the scene after the character reached a location?

Questions & Answers
1

I have a game, which has multiple scene. what i think is, when the character to go to a location, and the scene would change, and the character will spawn in the new scene, how do i write script?

2

create a boxcollider, scale it and place at the end.
check isTrigger in Inspector to true.
create a script attach it to the boxcollider.

here is untested code:

using UnityEngine;
using System.Collections;

public class EndOfLevel: MonoBehaviour {
    public string Level = "Level 0";

    void OnTriggerEnter(Collider other) {
        if (other.gameObject.CompareTag("Player"))
           Application.LoadLevel(Level);
    }
}

Sources:

http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.OnTriggerEnter.html
http://unity3d.com/support/documentation/ScriptReference/GameObject.CompareTag.html
http://unity3d.com/support/documentation/ScriptReference/Application.LoadLevel.html

hope it helps!