Hello and good evening @JhonaOB1993
First of all I you like to give kudos to Microsoft for the Power Apps Portals Documentation https://docs.microsoft.com/en-us/powerapps/maker/portals/. They inherited a lot from adxstudio, adopted it and built on it. It is my number one tool and I have it open at all times. The page also give a great overview of all the resources you would need to get started.
If I was starting to learn portals now I would start at the recently updated Microsoft Learn "Get started with Power Apps Portals" https://docs.microsoft.com/en-us/learn/paths/get-started-power-apps-portals/ where there is a learning path with 5 modules on Power Apps Portals.
While you go through the material at LEARN it's great to have your own portal to play around with. Get started with a free trial at https://powerapps.microsoft.com/en-us/portals/ that you can explore and destroy as much as you like, and let it go 30 days later.
The top two guys to follow
Nick Doelman (Twitter handle @readyxrm) is a certified trainer and wrote the book on Portals (well, he recently updated the content in LEARN) and he will respond to any questions with #PowerAppsPortals on Twitter. His blog https://readyxrm.blog/ will provide answers to the most basic and most advanced stuff, and being MVP he always cover the first things first.
Nicholas Hayduk (Twitter handle @Engineered_Code) post a new tip every week in his channel https://www.youtube.com/c/EngineeredCode (currently at 83 and counting..) and will provide some great cheats and insights into portals.
When you get confused about the different interfaces for configuring Power Apps Portals you can have a look at my blog post https://ulrikke.akerbak.com/2019/11/28/map-to-configuring-power-app-portals/ where I illustrate and describe what they are for. You can reach me on Twitter handle @UlrikkeAkerbk.
Good luck and have fun!
