How to call Class specific methods from an object stored in a GameObject[]?

Hey all.

I'm brand new to Unity, so I'm just doing a Tic Tac Toe game to learn the basics.

Everything is working up until I try to reference a Square in the array. I'm having trouble finding a way to store object (Square) references in such a way they can be accessed from their container, called Square_Boss, which is just an empty GameObject with an attached script. The Squares are Cubes I have all set up in the editor; a 2D scene.

I plan to use Square_Boss to hold the win condition logic, which is why I need the array in the first place.

 public class Square_Boss : MonoBehaviour
 {
     public GameObject[] squares;
 
 
         //initialization
         void Start ()
         {
                 squares = GameObject.FindGameObjectsWithTag ("SQU");
         }
 
         public static void Win ()
         {
                 int[] states = new int[9];
 
                 for (int i = 0; i < squares.Length; i++) {
                         states [i] = squares [i].getClickedBy ();
                         Debug.Log (states [i]);
                 }
         }
 }
 

The Square class looks like this:

 public class Square : MonoBehaviour
 {
         private bool isClicked = false;
         private int clickedBy = 0;
         private Color[] theColors = {Color.white, Color.red, Color.blue};
         private static int playerNumber = 1;
         private static int clicks = 0;
 
         // Use this for initialization
         void Start ()
         {
                 renderer.material.color = theColors [0];
         }
 
         private void OnMouseDown ()
         {
                 if (clicks < 9) {
                         if (!isClicked) {
                                 SetState ();
                         }
                 }
         else SendMessageUpwards("Win");
         }
 
         private void SetState ()
         {
                 if (playerNumber == 1) {
                         renderer.material.color = theColors [1];
                 } else {
                         renderer.material.color = theColors [2];
                 }
                 isClicked = true;
                 clickedBy = playerNumber;
                 ChangePlayer ();
         }
 
         private void ChangePlayer ()
         {
                 if (playerNumber == 1) {
                         playerNumber = 2;
                 } else {
                         playerNumber = 1;
                 }
         }
 
         public bool getClicked ()
         {
                 return isClicked;
         }
 
     public int getClickedBy ()
     {
         return clickedBy;
     }
 }
 

How do I make it so I can store references to the Squares and call their public methods from the Square_Boss script? When I try to make the array type Square[] it gives me an error about implicit casting or something (can't remember exactly, I tried that a while ago).

This is my first question on here, so I apologize for the noob mistakes. I looked around for answers but none of them made sense to me out of context. Also, sorry if the indents are weird... I made the mistake of telling MonoDevelop to format my code for me. =P