{ First we need to tell the Application object the name
 of the Help file and where to locate it. }
Application.HelpFile := ExtractFilePath(Application.ExeName) + 'YourHelpFile.hlp';
{ To Show a help file's content tab: }
Application.HelpCommand(HELP_CONTENTS, 0);
{ To display a specific topic of your help file: }
Application.HelpJump('TApplication_HelpJump');

procedure TForm1.Contents1Click(Sender: TObject);

begin

 Application.HelpCommand(HELP_CONTENTS, 0);

end;

procedure TForm1.SearchforHelpOn1Click(Sender: TObject);

begin

 Application.HelpCommand(HELP_PARTIALKEY, 0);

end;

procedure TForm1.HowtoUseHelp1Click(Sender: TObject);

begin

 Application.HelpCommand(HELP_HELPONHELP, 0);

end;