Sample usage!

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private SudokuBoard _board;
        private SudokuSolver _solver;

        private void Form1_Load(object sender, EventArgs e)
        {
            _board = new SudokuBoard(20, 20)
            {
                Text = "Sudoku!",
                Location = new Point(5, 5)
            };

            Controls.Add(_board);

            _solver = new SudokuSolver(_board);
            _solver.GameCompleted += SolverOnGameCompleted;
        }

        private void SolverOnGameCompleted(int numOfTrials)
        {
            MessageBox.Show(string.Format("No. of trials: {0}", numOfTrials));
        }

        private void button2_Click(object sender, EventArgs e)
        {
            _board.ClearBoard();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            _solver.Solve();
        }
    }