This question doesn't make sense. You write in Spanish the same way you write in English, only in Spanish :$ Translation of question: Como se escribe.... en espanol? = How do you write....in Spanish? (accent on 1st 'o', tilde, ~, over final 'n')
"September 17, 2009" in Spanish is "septiembre diecisiete de dos mil nueve". It is pronounced "sep-tee-EM-bray dee-ess-ee-see-EH-tay day dose meel new-AY-bay". Please see the Related link below for confirmation of the translation.