How can my Brazilian girlfriend come to America?

OK so you can sponsor her for a fiancée visa, but the requirement is that in order to do that you need to have physically met within the last two years. Once that physical meeting has taken place, then you can sponsor her for her Fiancée visa. Now if you are not serious about marrying her presently, then she can simply apply at the US consulate in Brazil for a tourist visa. She will have to show that she has a job and property in order to convince the consulate that she Will return to Brazil after her trip is finished.