I need suggestions on how to learn ST Microelectronics, what is the best way and what I should know before I learn.

 

https://en.m.wikipedia.org/wiki/STMicroelectronics

Try getting a job there. It would be the quickest way to learn about them.
If they will not hire you, then use the link to read about them and learn about the company.

 

You have to ask how to learn ST Microcontroller(s) programming.

 

sounds like learning to ask questions clearly is a lot more important to you right now.