I have a C# project that uses a MdiContainer WinForm as the project's main shell form.

When the project to run, the main form starts up as expected. But how do I make another form (child form) also display at startup?

In my main form Main() method I do this to display the main form:
Application.Run(new MainForm());

This is fine, but I can't seem to issue that command again to start another form.