Use this text in project file. This example shows how to minimize non-main form in the running application.
program Project1; uses Forms, Windows, Messages, SysUtils, Classes, Graphics, Controls, Dialogs, Unit1 in 'Unit1.pas' {Form1}, Unit2 in 'Unit2.pas' {Form2}; {$R *.RES} begin Application.Initialize; Application.CreateForm(TForm1, Form1); Application.CreateForm(TForm2, Form2); Form2.Show; SendMessage(Form2.Handle,WM_SYSCOMMAND,SC_MINIMIZE,0); Application.Run; end.