How can an Afro-Brazilian states his ethinicity if Native Brazilians and Afro-Brazilians are not listed?

Ask EP to add those options into the enthinicity list. There's a group called "I want to improve the experience project"; ask for it there.

The url: http://www.experienceproject.com/group_profile.php?g=9556

I don't get it either. We were just talking about this very topic the other day. It irks me that the majority of blacks consider themselves African-American. They're not African. Not even close. They're American, born here, and will likely, the majority, never visit Africa either. My forefathers, were Romanian. I don't call myself Romanian-Canadian. I'm Canadian, from Romanian "DESCENT". Unless i was actually born there, then i'd call myself as such. And, like Afro-Brazilian, i think they should be Brazilian. I'm pretty mixed, as most of society is (whether they know it or not), and can you imagine me trying to put it all down? You are what you mostly are or are according to what country you were born in, regardless of mixture. I'm Canadian. JMO.

Depending on the form you're using, I might go with "Hispanic." Certainly, Hispanic represents more-or-less the same mix of cultures (Native American, black, and Western European) that an Afro-Brazilian likely has, so it's a passably close match.

Ideally, though, they'd just make "ethnicity" a write-in box and call it a day.

"Other", or don't answer. In this country, you get to choose whether or not you give your ethnicity.