how to make UI work like OnGui.

I been trying to figure out how to do something with Unity's UI that I could do in OnGUI.....I have a base item class with a variable for the icon. when using OnGUI its type was texture2d and I used a for loop with "if(GUI.button)" to display the images representing the items. I was wondering how I achieve the same results using UI.

In the base Item script: (OnGui version) --> private Texture2D _icon; (UI version)--> private Sprite _icon;

In the Chest script: (OnGui version) --> for(int i = 0; i < loot.Count; i++) { if(GUI.Button(new Rect(......), new GUIContent(loot[i]._icon) (UI version)--> ??????not really sure??????

EDIT : here is some snippets from my scripts so you see what I have going on kinda.

My item script has this (and a getter and setter) : private Sprite _icon;

This is my ItemGenerator script:

 using UnityEngine;
 using UnityEngine.UI;
 
 
 public static class ItemGenerator {
 
     public const int BASE_MELEE_RANGE = 1;
     public const int BASE_RANGED_RANGE = 5;
 
     private const string MELEE_WEAPON_PATH = "Items/Weapons/Melee/";
 
 
     public static Item CreateItem()
     {
 
 //decide what type of item to make
 
         //call the method to create that base item type
         Item item = CreateWeapon();
 
 
         //      _name;
         item.Value = Random.Range(1, 101);
         item.Weight = Random.Range(1, 21);
         item.Rarity = RarityTypes.Common;
 
 
 
 //return the new item
         return item;
     }
 
 
     public static Weapon CreateWeapon()
     {
         //decide if the weapon is melee or ranged
         Weapon weapon = CreateMeleeWeapon();
 
 
         //return the weapon created
         return weapon;
 
     }
 
     private static Weapon CreateMeleeWeapon()
     {
         Weapon meleeWeapon = new Weapon();
 
         string[] weaponNames = new string[4];
         weaponNames[0] = "Axe";
         weaponNames[1] = "Axe1";
         weaponNames[2] = "Dagger";
         weaponNames[3] = "Sword";
 
 
         //fill in all the values for that item type
         meleeWeapon.Name = weaponNames[Random.Range(0, weaponNames.Length)];
 
         //assign the max damage
         meleeWeapon.MaxDamage = Random.Range(5, 16);
         meleeWeapon.DamageVariance = Random.Range(.2f, .76f);
         meleeWeapon.TypeOfDamage = DamageType.Slash;
 
         meleeWeapon.MaxRange = BASE_MELEE_RANGE;
 
         //assign the icon for the weapon
         meleeWeapon.Icon = Resources.Load<Sprite>(MELEE_WEAPON_PATH + meleeWeapon.Name) ;
 
     
         //return melee weapon
         return meleeWeapon;
     }
 
 }
 
 
 public enum ItemType
 {
     Armor,
     Weapon,
     Potion,
     Scroll
 }

This is my Chest script:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 
 
 [RequireComponent (typeof(BoxCollider))]
 [RequireComponent(typeof(AudioSource))]
 public class Chest : MonoBehaviour {
 
 
     public enum State
     {
         open,
         close,
         inbetween
     }
 
     public AudioClip openSound;
     public AudioClip closeSound;
 
     public State state;
 
     public float maxDistance = 2.4f;           //Max distance the player can be to open this chest
 
     private GameObject _player;
     private Transform _myTransform;
     public bool inUse = false;
 
     private GameObject lootWindow;
     private GameObject LWitemHolder;
     public GameObject item;
 
     public bool _used = false;                 //track if the chest has been used or not
 
     public List<Item> loot = new List<Item>();
 
     // Use this for initialization
     void Start () {
         lootWindow = GameObject.Find("Loot Window");
         LWitemHolder = GameObject.Find("LW item Holder");
         _myTransform = transform;
         state = State.close;
 
         
 
     }
 
     // Update is called once per frame
     void Update () {
         if (!inUse)
         {
             return;
         }
 
         if (_player == null)
         {
             return;
         }
 
         if(Vector3.Distance(_myTransform.position, _player.transform.position) > maxDistance)
         {
             playerHUD.chest.ForceClose();
         }
         return;
     }
 
     public void OnMouseEnter()
     {
     }
 
 
     public void OnMouseExit()
     {
     }
 
 
     public void OnMouseUp()
     {
 
         GameObject go = GameObject.FindGameObjectWithTag("Player");
 
         if(go == null)
         {
             return;
         }
         if(Vector3.Distance(_myTransform.position, go.transform.position) > maxDistance && !inUse)
         {
             return;
         }
 
 
         switch (state)
         {
             case State.open:
                 state = State.inbetween;
                 ForceClose();
                 break;
             case State.close:
                 if(playerHUD.chest != null)
                 {
                     playerHUD.chest.ForceClose();
                 }
                 state = State.inbetween;
                 StartCoroutine("Open");
                 break;
         }
     }
 
     private IEnumerator Open()
     {
   //set this script to be the one that is holding the items
         playerHUD.chest = this;
 
   //find the player so its distance can be trcked after opening the chest
         _player = GameObject.FindGameObjectWithTag("Player");
 
         inUse = true;
 
         GetComponent<Animation>().Play("open");
         GetComponent<AudioSource>().PlayOneShot(openSound);
 
         if (!_used)
         {
         PopulateChest(5);
         }
 
    //wait until the chest is done opening
         yield return new WaitForSeconds(GetComponent<Animation>()["open"].length - .5f);
         state = State.open;
 
         Messenger.Broadcast("DisplayLoot");
     }
 
     private void PopulateChest(int x)
     {
 
         
         for (int cnt = 0; cnt < x; cnt++)
         {
             loot.Add(ItemGenerator.CreateItem());
             loot[cnt].Icon = Instantiate(loot[cnt].Icon);
    //         if (loot[cnt].Icon == null)
    //         {
     //            loot[cnt].Icon = Instantiate(item) as GameObject;
     //            loot[cnt].Icon.transform.SetParent(LWitemHolder.gameObject.transform, false);
     //        }
      //       loot[cnt].Name = "I:" + Random.Range(0, 100);
     //      item = Instantiate(item);
    //        item.transform.SetParent(LWitemHolder.transform, false);
            item.name = loot[cnt].Name;
         }
         _used = true;
         //      loot.ForEach((Item) => { Instantiate(item); });
           
 
 
     }
 
     private IEnumerator Close()
     {
         _player = null;
         inUse = false;
 
         GetComponent<Animation>().Play("close");
         yield return new WaitForSeconds(GetComponent<Animation>()["close"].length);
         GetComponent<AudioSource>().PlayOneShot(closeSound);
         state = State.close;
 
    //     for (int cnt = 0; cnt < loot.Count; cnt++)
    //     {
   //          Destroy(item);
   //      }
         
     }
 
     public void ForceClose()
     {
         Messenger.Broadcast("CloseChest");
 
         StopCoroutine("Open");
         StartCoroutine("Close");
 
     }
 
 
 
 }

The commented out code above is different things that only partially worked.