The game links this guide, which explains how the multiplayer system works:
https://docs.google.com/document/d/1rAeuk7qFinUyPRJGk4x6Dim3rmQN2zoLaR3PNR0roU4

You most likely need to add port forwarding to your router if you want to host your world on your computer and let other players join from outside your LAN (same goes for your friend, if they want to host it).

If the guide isn't enough to sort things out or you need additional help, the best way would be via a live support session on Discord - entuland#7134 - there we can have a voice chat with screen sharing and I could guide you through the various checks.

I understand some Portuguese but I can't really speak it properly - if you don't know any English / Spanish / French / Italian then you may need to find a friend who speaks any of those languages to help us communicate during the live support session - though if you understand some Spanish and can tolerate me butchering your language we may give it a try without anyone else.