So my name is written Anibal, I'm from Brazil, just so you know. I'd like to know how would you write it in japanese, I'm in doubt between A-ni-ba-ru and A-ni-ba-e-ru. Any further explanation would be much appreciated.
For this kind of question, you can start by seeing how other people spell it. I searched the Japanese Wikipedia for Anibal. Here were the top two results:
How you transcribe a name usually depends on its pronunciation, not its spelling, so it's possible that an Anibal from a different region would have a different transcription. But you said you're from Brazil, and so is the second person I linked to above, so it seems reasonable to spell your name the same way as his. And that's true regardless of whether it's based on spelling or pronunciation--following convention in transcribing names is usually a good thing. So based on this, I think アニバル seems like a good spelling.
If you can't read katakana, that's A-ni-ba-ru, just like your first guess. That would usually be written without hyphens, so it's Anibaru.
As far as I know, the final L is pronounced [u], so that Anibal could also be アニバウ (A-ni-ba-u), which represents the pronunciation more faithfully than アニバル (which sounds more like Anibaru, when pronounced as a Portuguese speaker would).