UI AND UNITY POSITION

I have this problem, that I want to be able to click on a "tile" on the screen and then a pop-up menu should be shown just next to the tile. I can click on the tile and then a pop-up menu shows up but not where I want it.

On the picture below I've clicked on the top left one.

My code for placing the picture is as following:

using UnityEngine; using System.Collections;

public class TowerMenu : MonoBehaviour { bool showMenu = false; float x; float y; GUIStyle myStyle;

 public Texture2D[] towers;

 void OnGUI()
 {
     if(showMenu)
     {
         //Bear tower
         GUI.Button(new Rect(x + 10, y - 25, 50, 50), towers[0]);
         //Seal tower
         GUI.Button(new Rect(x + 10, y + 25, 50, 50), towers[1]);
     }
 }

 public void ShowMenu(Vector2 pos)
 {
     showMenu = true;
     x = pos.x;
     y = pos.y;
 }

}

Hope anyone can help me