help with macbook air

[kaue at digirati.com.br]

Hello,

I am from Brazil and i got a macbook air.. its seems running nice but
I
cant type "dead keys" I am in trouble cause i really need type words
like:



não, atenção, é 



But when i try to type "dead keys" it comes like n~ao, aten'c~ao,
'e... so there is any advice to me?



Thanks