How can i edit and develope the core code?

How can i edit and develope the core code?

Hi,
I wanna contribute in the core development. So, i started to read the documents but i got confused and i have some important questions :
  • Which IDE should i use for coding?
  • How can i be one of the contributor? because my name is not between the contributor of core.js . How should i apply for being a contributor ?
Please, introduce me a helpful document that guide me step by step for know how can i contribute,edit,develop and publish codes.
Thank you