I want to start making a custom recoveries and/or custom roms but need help

So I want to get into android developing really heavily and want to make things from complete scratch.things such as custom recoveries and custom roms. I want to know where to start.
Is this a good spot to start?:
https://source.android.com/

Just need some direction and help or direction would be greatly appreciated.

Unable to use any recoveries other then stock

I have flashed the newer firm ware but when I installed a MM rom exodus and now I wasnt able to use the recovery any more. I have tried flashing other recoveries but the only one that worked is the stock recovery

Samsung Galaxy S7 Edge SM-G935 All-in-One thread ROMs Recoveries

:):):)
Hi all S7 Edge owners!

Let's discuss and share all we know about Galaxy S7 Edge:
Model SM-G935F
Chip Exynos
Codename hero2lte

SM-G935
ROM
Recovery
Root
Kernels

Let me know if I'm missing anything, I will add here.

ROM

1. Stock
Official Samsung Android version 6.0.1 G935FXXU1APEQ available through SamMobile

2. Renovate Edge
Android 6.0.1
http://forum.xda-developers.com/s7-e...g935f-t3339149

Recovery

1. TWRP 3.0.2-2
http://forum.xda-developers.com/s7-e...0-0-0-t3334084


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