How to access a non-static variable from another class?

Hello I am trying to make a simple menu script that goes to the level picked and changes the material of a game object. Do this I have created five scripts. Here is the code for the first one

 #pragma strict
 var Level_Select : int;
 
 function Start () {
 
 }
 
 function Update () {
 
         if (Input.GetKey ("up"))
         {
         Level_Select--;
         Debug.Log (Level_Select);
         }
             
             if (Input.GetKey ("down"))
         {
         Level_Select++;
         Debug.Log (Level_Select);
         }
 
         if (Level_Select == 1)
         {
         renderer.material.color = Color.grey;
         }
         else
         {
         renderer.material.color = Color.black;
         }
         
 }

Then in the other scripts the code is

 #pragma strict
 
 function Start () {
 
 }
 
 function Update () {
 
         if (Input.GetKey ("up"))
         {
         Main_Menu_Script.Level_Select--;
         Debug.Log (Main_Menu_Script.Level_Select);
         }
             
             if (Input.GetKey ("down"))
         {
         Main_Menu_Script.Level_Select++;
         Debug.Log (Main_Menu_Script.Level_Select);
         }
 
         if (Main_Menu_Script.Level_Select == 2)
         {
         renderer.material.color = Color.grey;
         }
         else
         {
         renderer.material.color = Color.black;
         }
         
 }

Then the other 3 scripts are similar to the last one just with "Level_Select" being a different number. I haven't added the code to change the level yet.

When the Level_Select variable isnt static I get the error "Assets/Scripts/Main Menu/Main_Menu_Script_2.js(21,38): BCE0020: An instance of type 'Main_Menu_Script' is required to access non static member 'Level_Select'." When I change the Level_Select variable to a static variable all the errors go away. So my question is, is it possible to access a non static variable in another script and if it is possible, how. Thank You