How Is This Done...

hi guys...i want to make a menu like this:http://www.templatemonster.com/flash-te ... 14616.htmlthe rollover effect is not important for me... but when u click a button from the menu is selected and than when u click another button the previous one is deselected and the new one selected so viewers would know at which page they are at the moment(u know like visited link or smth from html);i cant figure it out ... any ideas or link to any helpful tutorial???