On a PC, if you switch the keyboard setting to Canadian standard multilingual (Clavier canadien multilingue standard):
ctrl + e = œ
ctrl + shift + e = Œ
I'm come to love this keyboard configuration. It's essentially the same as American English (QWERTY), so there's no real learning curve if that's what you're familiar with (not sure what you use in Brazil, but you write well in English). But it makes typing symbols common to other languages, like é, ç, ñ, ß, ø, €, etc, very simple.