更新图片框

我希望我的图片框每 2 秒更新一次其字符串/文本（并删除旧文本）。 我在这里做了一些代码，但它没有显示任何内容：

namespace WindowsFormsApplication2
public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
               }
    private void Form2_Load(object sender, EventArgs e)
    {
    }
    static System.Windows.Forms.Timer myTimer = new System.Windows.Forms.Timer();
    static bool exitFlag = false;
    private void TimerEventProcessor(Object myObject, EventArgs myEventArgs)
    {
        var image = new Bitmap(this.pictureBox1.Width, this.pictureBox1.Height);
        var font = new Font("TimesNewRoman", 30, FontStyle.Bold, GraphicsUnit.Pixel);
        var graphics = Graphics.FromImage(image);
        graphics.DrawString("Hi", font, Brushes.White, new Point(350, 0));
        this.pictureBox1.Image = image;
        System.Threading.Thread.Sleep(1000);
        pictureBox1.Invalidate();
        graphics.DrawString("Tell me your name...", font, Brushes.White, new Point(100, 0));
        this.pictureBox1.Image = image;
        this.pictureBox1.Update();
        this.pictureBox1.Refresh();
        //dialog box in here
    }
      public  int ActivateTimer()
 {
   myTimer.Tick += new EventHandler(TimerEventProcessor);
    myTimer.Interval = 1000;
    myTimer.Start();
    while (exitFlag == false)
     {
        Application.DoEvents();
   }
    return 0;
 }