creating a word factory game

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        const int GridHeight = 8;
        const int GridWidth = 8;
        string[,] GameGrid = new string[GridHeight, GridWidth];
        public Form1()
        {
            //need a text box and a button
            InitializeComponent();
            textBox1.Height = 200;
            textBox1.Width = 200;
            textBox1.Multiline = true;
        }




        private void button2_Click(object sender, EventArgs e)
        {

            ShuffleGrid();
            printGrid();
        }

        private void printGrid() {
            textBox1.Text = "";

            for (int ar1 = 0; ar1 < GridHeight; ar1++)
            {
                for (int ar2 = 0; ar2 < GridWidth; ar2++)
                {



                    textBox1.Text += GameGrid[ar1, ar2];

                }
                textBox1.Text += Environment.NewLine;

            }

        }
        private void ShuffleGrid() {
            textBox1.Text = "";
            Random r = new Random();
            for (int ar1 = 0; ar1 < GridHeight; ar1++)
            {
                for (int ar2 = 0; ar2 < GridWidth; ar2++)
                {
                    int i =r.Next(65, 93);
                    GameGrid[ar1, ar2] =  ((char)(i)).ToString();
                }
            }
        }

    }
}