As with your other question about the mouse-over event, your english unfortunately makes it hard to understand fully what it is you want to do..

For the sake of an answer to one possible question: If what you want is to rotate your camera around an object like it's "orbiting" around it, you could start by getting your camera to always look at the object. You can do that pretty simple with the Transform.LookAt() function.

The part about if the mouse is on the right hand side of the screen you could use Input.mousePosition. A simple script for this would be something like this:

using UnityEngine;
using System.Collections;

public class mousePosition : MonoBehaviour {

    private Vector3 position;

    // Use this for initialization
    void Start () {

    }

    // Update is called once per frame
    void Update () {

       position = Input.mousePosition;

       if (position[0] <= Screen.width/2){
         print("Left side..");
       }

       else if (position[0] >= Screen.width/2) {
         print("Right side..");
       }
    }  
}

All you have to do with the script is to add the rotation that you want around your object..