Possibly you will come to Brazil not only for the congress, but will add a few days for traveling. If you havent made up your mind already on where to go and what to see, check out the site Visit Brazil, the official websiote of the Ministry of Tourism:
http://www.visitbrasil.com/en/
In any case, make sure ahead of time whether or not you will need a tourist visa for your stay. Please inquire at your local Consulado Geral do Brasil.