thanks for your kindly answer
now i’m not a web designer full time, i’m a marketing student and i want specialize me in web marketing and comunication.
anyway thanks for html tips, now is validate but the bottom triangle in menu give me problem in IE 8 now 
and so i’ve opted to an alternative shyle sheet to hidden this element.
i eliminated the .main margin-top in ie7 style sheet but nothing happens
thanks again for your support