MessageBox

 private void validateUserEntry2()
    {

        // Checks the value of the text.

        if(serverName.Text.Length == 0)
        {

            // Initializes the variables to pass to the MessageBox.Show method.

            string message = "You did not enter a server name. Cancel this operation?";
            string caption = "No Server Name Specified";
            MessageBoxButtons buttons = MessageBoxButtons.YesNo;
            DialogResult result;

            // Displays the MessageBox.

            result = MessageBox.Show(this, message, caption, buttons,
                MessageBoxIcon.Question, MessageBoxDefaultButton.Button1,
                MessageBoxOptions.RightAlign);

            if(result == DialogResult.Yes)
            {

                // Closes the parent form.

                this.Close();

            }

        }





C#]
protected void button1_Click(object sender, System.EventArgs e) {
   if(textBox1.Text == "") {
      MessageBox.Show("You must enter a name.", "Name Entry Error",
         MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
   }
   else {
      // Code to act on the data entered would go here.
   }
}