OscMax 2.51 Menu

Must be familar with OscMax 2.51 which is different from Oscommerce. I need the categories box when clicked on the first level category the page does not change only the sub-Categories drop down in the menu. When click on first level category again the menu closes the sub-Categories. I do not want the first level category to show anything but a name. I attach an image to show what i want