lol, I feel like I see this question come up a lot and searched for previous threads and saw you posted in it already awhile back
If you didn't get much from there I doubt you'd get much from a new thread
I have no first hand experience with Neo development, but googling it there's both a pretty damn comprehensive dev wiki and a community devkit for C/C++ coding
wiki.neogeodev.org
Open source development for Neo-Geo. Contribute to dciabrin/ngdevkit development by creating an account on GitHub.
github.com
Both of those should absolutely be where you start reading, and if none of it is making sense or seems like too much work then I would abort mission now. If you just want to "make a game" then start with something like Godot or GameMaker, don't set yourself up for failure by trying to make a Neo game right off the bat if you've never tried making a game before
If you really want to do retro hardware I wouldn't even start with the Neo, start with something like the Sega Genesis
SGDK - A free and open development kit for the Sega Mega Drive - GitHub - Stephane-D/SGDK: SGDK - A free and open development kit for the Sega Mega Drive
github.com
It'll be simpler for a beginner, there's way more resources on the internet for help and the Neo and Genesis share the same Main CPU so it'd be a better place to start and you can carry the experience over
Good luck!