Look for your main program (in our case main.cs). It would have code similar to this

static class BDMain
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [MTAThread]
        static void Main()
        {
            Application.Run(new OrdersMain());
        }
    }

This is where you can give a different form to run first. I'm not sure of a simpler and better way to test the form individually, though there may be.