If you actually want Yes and No buttons (and assuming WinForms):
void button_Click(object sender, EventArgs e)
{
var message = "Yes or No?";
var title = "Hey!";
var result = MessageBox.Show(
message, // the message to show
title, // the title for the dialog box
MessageBoxButtons.YesNo, // show two buttons: Yes and No
MessageBoxIcon.Question); // show a question mark icon
// the following can be handled as if/else statements as well
switch (result)
{
case DialogResult.Yes: // Yes button pressed
MessageBox.Show("You pressed Yes!");
break;
case DialogResult.No: // No button pressed
MessageBox.Show("You pressed No!");
break;
default: // Neither Yes nor No pressed (just in case)
MessageBox.Show("What did you press?");
break;
}
}