How to make my cards dragable in my solitaire game?

Hi im making a solitaire game but i dont know how to make my cards dragable

 using UnityEngine;
 using System.Collections;
 
 public class SetupCards : MonoBehaviour 
 {
     int numberOfCards = 52;
     int numberOfCardSorts = 4;
     public float verticalSize = 1.4f;
 
     // Use this for initialization
     void Start() 
     {
         
     }
 
     // Update is called once per frame
     void Update() 
     {
         
     }
 
     void OnGUI()
     {
         int currentSort = 0;
         int cardNumber = 0;
 
         for (int i = 0; i < numberOfCards; ++i)
         {
             int numberOfCardsPerSort = numberOfCards / numberOfCardSorts;
             float cardSizeX = Screen.width / numberOfCardsPerSort;
 
             if (cardNumber == numberOfCardsPerSort)
             {
                 ++currentSort;
                 cardNumber = 0;
             }
 
             Vector2 cardSize = new Vector2(cardSizeX, cardSizeX * verticalSize);
 
             Rect rect = new Rect(
                 cardSize.x * cardNumber,
                 cardSize.y * currentSort,
                 cardSize.x,
                 cardSize.y);
 
             string texturePath = "Textures/cards/";
 
             switch (currentSort)
             {
                 case 0:
                     texturePath += "diamond/diamond_";
                     break;
 
                 case 1:
                     texturePath += "clover/clover_";
                     break;
 
                 case 2:
                     texturePath += "heart/heart_";
                     break;
 
                 case 3:
                     texturePath += "spade/spade_";
                     break;
             }
 
             texturePath += cardNumber.ToString();
 
             //Debug.Log(texturePath);
 
             Texture texture = Resources.Load(texturePath) as Texture;
 
             GUI.Label(rect, texture);
 
             ++cardNumber;
         }
     }
 }