procedure TForm1.Button1Click(Sender: TObject);
var
  Button: TButton;
  Group: TRibbonGroup;
  TabItem: TRibbonTabItem;
begin
  TabItem := Ribbon1.Tabs.Add;
  TabItem.Caption := 'Tab caption';
  // let the controls be owned by the ribbon control
  Group := TRibbonGroup.Create(Ribbon1);
  // in the reference for the TRibbonGroup class is mentioned "Ribbon groups are placed on a ribbon page",
  // so let's do it so
  Group.Parent := TabItem.Page;
  Group.Caption := 'Group caption';
  // let the controls be owned by the ribbon control
  Button := TButton.Create(Ribbon1);
  Button.Parent := Group;
end;