Simply question about spinning

Greetings unity community, i am fairly new to the unity program and i have a “simple” task to finish. I was searching here for my solution but didn’t found any.

My task is to randomly spin a object at mouse click. The object should spin like a roulette and stop after few spins. I tried with the rotate + random.range functions but it just rotates the object without spinning, so i need some acceleration and decelerations.

Any help is greatly appreciated. Thank you.

with some tutorials i created this:

using UnityEngine;
using System.Collections;

public class Spin : MonoBehaviour
{
public float turnspeed = 50f;

void Update ()
{
	if (Input.GetMouseButtonDown (0))
		transform.Rotate(Vector3.up, Random.Range (50, 800) * turnspeed * Time.deltaTime);

	}

}

but with this script my object rotates instantly to a random value. I need to see it spinning and slowly decelerating after 2-3 spins.