@Sailing_Nut
Arcade ROMS are confusing at first and there are a LOT of questions. The Admins have put together a lot of documentation to help people out and unfortunately, there are a lot of people that just expect the admins to do everything for them, Unfortunately, the Admins don't get paid and the expectation to have everything handed to people is getting really common these days.
Just as an FYI, The extra instructions are located under the individual emulators. For instance, MAME and FBA have the managing roms link. Other emulators have instructions for specific configs and such.
You can also always Google "Retropie MAME" or "Retropie N64" to get to the direct links as well.