How do i get texture from GUI box?

Hi, i have an array of flags(245) and i have them in gui box.I need when i click on the box then the script grabs the texture from the box and put them into the material, any idea?

Thanks

 using UnityEngine;
 using System.Collections;
 
 public class GUIEleveation : MonoBehaviour {
 
     public GUISkin skin;
 
     public string name;
 
     public Texture2D w1, w2, w3, w4, m1, m2, m3, m4;
     public Texture2D[] flags;
     public Texture2D selectedFlag;
 
     public Vector2 scroll;
 
     public int progress;
 
     void OnGUI () {
         GUI.skin = skin;
 
         switch (progress) {
 
         case 0:
             // Name Panel
             GUI.Box(new Rect(Screen.width /2-200,Screen.height /2-200,400,400),"User Info");
             name = GUI.TextField(new Rect(Screen.width/2-150, Screen.height/2-33.3f, 300, 50), name, 20);
             if (GUI.Button(new Rect(Screen.width/2-150, Screen.height/2+100, 300, 50), "Next")) {progress = 1;}
             break;
 
         case 1:
             // Portret Select
             GUI.Box(new Rect(Screen.width/2-400,Screen.height/2-300,800,600),"Portret");
             GUILayout.BeginArea(new Rect(Screen.width/2-400,Screen.height/2-270,800,600));
             GUILayout.BeginHorizontal();
             GUILayout.Box(w1,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.FlexibleSpace();
             GUILayout.Box(w2,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.FlexibleSpace();
             GUILayout.Box(w3,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.FlexibleSpace();
             GUILayout.Box(w4,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.EndHorizontal();
             GUILayout.EndArea();
 
             GUILayout.BeginArea(new Rect(Screen.width/2-400,Screen.height/2-50,800,600));
             GUILayout.BeginHorizontal();
             GUILayout.Box(m1,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.FlexibleSpace();
             GUILayout.Box(m2,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.FlexibleSpace();
             GUILayout.Box(m3,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.FlexibleSpace();
             GUILayout.Box(m4,GUILayout.Height(190),GUILayout.Width(190));
             GUILayout.EndHorizontal();
             GUILayout.EndArea();
 
             if (GUI.Button(new Rect(Screen.width/2-150,Screen.height/2+200,300,50),"Next")) {progress = 2;}
             break;
 
         case 2:
             // Flag Selection
             GUI.Box(new Rect(Screen.width/2-450,Screen.height/2-300,900,600),"Flag");
             GUILayout.BeginArea(new Rect(Screen.width/2-425,Screen.height/2-225,850,450));
             scroll = GUILayout.BeginScrollView(scroll);
             foreach (Texture2D flag in flags) {
                 GUILayout.Box(flag);
             }
             GUILayout.EndScrollView();
             GUILayout.EndArea();
             if (GUI.Button(new Rect(Screen.width/2-150, Screen.height/2+233.33f, 300, 50), "Next")) {progress = 3;}
             break;
 
         case 3:
             // Main Menu
             GUI.Box(new Rect(Screen.width/2-200, Screen.height/2-150, 400, 250), "Main Menu");
             GUILayout.BeginArea(new Rect(Screen.width/2-150, Screen.height/2-75, 300, 150));
             if (GUILayout.Button("Start Game", GUILayout.Width(300), GUILayout.Height(50))) {}
             GUILayout.FlexibleSpace();
             if (GUILayout.Button("Options", GUILayout.Width(300), GUILayout.Height(50))) {progress = 4;}
             GUILayout.EndArea();
             break;
 
         case 4:
             //Options
             GUILayout.BeginArea(new Rect(Screen.width/2-350, Screen.height/2-300, 700, 600));
             GUILayout.Box("Options", GUILayout.Width(700), GUILayout.Height(600));
             GUILayout.EndArea();
             break;
 
         }
     }
 }