You can use
MessageBox.Show Method (IWin32Window, String)
to display a message box in front of the specified object and with the specified text. Such as
MessageBox.Show(new Form() { TopMost = true }, "Your text here!");
But I would rather prefer to create my own messagebox from a from which basically acts like a message box. After creating it set its TopMost property to true and call it with the .ShowDialog() method.
Good luck,
OI