A crash course on how to desgn a custom MCU controller?

[Kiri]

I understand pin goes to pin, but everything else is confusing and a blur to me. It would be nice if I could receive help so I can continue the custom PCB I am currently designing. I have intermediate knowledge in electronics so any links to good reads and or help to design the controller part give me much help. Thank you.

[vvp]

Find an introductory application note for your MCU and read it. E.g. AN4206 for STM32F3 (if you happen to use STM32F3 MCU). You can also make your design by modifying the schematic of an existing breakout board for your MCU.