Block Selecting and Moving

I'm making game like Battleship Craft in Appstore. I'm working on block editing in game. I made block generating and destroying but I can't make block selecting and moving. This is my Script.

 #pragma strict
 
 var Block:Transform;
 var ToolSelected:float=1;
 
 function Start () {
     
     Instantiate(Block, Vector3(0.5, 0.5, 0), Quaternion.identity);
     Instantiate(Block, Vector3(0.5, 0.5, 1), Quaternion.identity);
     Instantiate(Block, Vector3(-0.5, 0.5, 1), Quaternion.identity);
     Instantiate(Block, Vector3(-0.5, 0.5, 0), Quaternion.identity);
     Instantiate(Block, Vector3(0.5, -0.5, 0), Quaternion.identity);
     Instantiate(Block, Vector3(0.5, -0.5, 1), Quaternion.identity);
     Instantiate(Block, Vector3(-0.5, -0.5, 1), Quaternion.identity);
     Instantiate(Block, Vector3(-0.5, -0.5, 0), Quaternion.identity);
     
 }
 
 function Update () {
 
     if(Input.GetKeyDown(KeyCode.Alpha1)){
         ToolSelected=1;
     }
     if(Input.GetKeyDown(KeyCode.Alpha2)){
         ToolSelected=2;
     }
     if(Input.GetKeyDown(KeyCode.Alpha3)){
         ToolSelected=3;
     }
 
     if (Input.GetMouseButtonDown(0)) {
        var hit : RaycastHit;
        var ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        var BlockDir=transform.TransformDirection(Vector3.forward);
        
        if(Physics.Raycast(ray, hit)){
            if(ToolSelected==1){
                Instantiate(Block, hit.collider.transform.position+hit.normal.normalized, Quaternion.identity);
            }
            if(ToolSelected==2){
                Destroy(hit.collider.gameObject);
            }
            }
            
     }
        
 }