Resource for basic info on Amazon and POD?

I’m very new to selling on Amazon and have a lot of questions about basic stuff (professional vs individual, GTIN exemption, branding, FBA, Amazon Merch, etc – basically everything!), particularly related to print on demand. Can anyone recommend a good video series or something similar that breaks it all down in an easy-to-understand way? I find Amazon’s own explanation pages confusing because it feels like they always assume a basic level of knowledge about something else and I end up having to chase down terms I don’t understand. Appreciate any recommendations you all have, thanks.