How to put the player in pandom now busy area of the play field?

I'm new to Unity, trying to make the Bomberman game. I have the field, containing of tiles, concrete walls and brick walls. Now I want to put the player in a free area. But how player controller can know what tile is free and what is not? Here is my BrickWallView code:

 public class BrickWallView : MonoBehaviour {
 
     public GameObject brickWall;
     public int numberOfWalls;
     private float y = 0.5f;
     private bool[,] wallMap;
     // Use this for initialization
     void Start () {
         wallMap = new bool[GlobalParameters.numberTilesX, GlobalParameters.numberTilesZ];
         PlaceWalls();
     }

 void PlaceWalls()
     {
          
         for (int i = 0; i < numberOfWalls; i++)
         {
             int x = -1;
             int z = -1;
             do
             {
                 x = (int)Random.Range(1, GlobalParameters.numberTilesX - 1);
                 z = (int)Random.Range(1, GlobalParameters.numberTilesZ - 1);
             } while (x % 2 == 0 || z % 2 == 0 || wallMap[x, z]);
             wallMap[x, z] = true;
             Clone(x, z);
         }
     }

 void Clone(int x, int z)
     {
         GameObject brickWallClone = (GameObject)Instantiate(brickWall, new Vector3(x, y, z), brickWall.transform.rotation);
         brickWallClone.SetActive(true);
     }
 }