How to rotate right and left

Hi guys, can u tell me how should i do to rotate the camera (in-game) when i move the mouse right or left? Here there is my code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Sparo : MonoBehaviour {
6.     public float velocita = 10.0f;
7.     public float potenzaProiettile = 1000.0f;
8.     public Rigidbody proiettile;
9.     public Transform arma;
10.    
11.     // Use this for initialization
12.     void Start () {
13.        
14.     }
15.    
16.     // Update is called once per frame
17.     void Update () {
18.  
19.         //programmo i movimenti
20.         float movimentoOrizzontale = Input.GetAxis("Horizontal") * (velocita * Time.deltaTime);
21.         float movimentoVerticale = Input.GetAxis("Vertical") * (velocita * Time.deltaTime);
22.  
23.         transform.Translate(new Vector3(movimentoOrizzontale, 0.0f, movimentoVerticale));
24.  
25.  
26.         if (Input.GetButtonUp("Fire1"))
27.         {
28.             Rigidbody sparato = Instantiate(proiettile, arma.position , Quaternion.identity) as Rigidbody;
29.             sparato.AddForce(Vector3.forward * potenzaProiettile);
30.         }
31.        
32.     }
33. }
34.  

This is the code to make my Camera shoot a sphere when i press the left mouse button... and i neet to rotate my camera too...

 

Not at my PC but you can use use Input.GetAxis("Mouse X") to get the current movement of the mouse left and right and then you just need to += that onto the camera transforms rotation on the z axis.