I would suggest starting off by reading the first few chapters of the official elisp manual https://www.gnu.org/software/emacs/manual/elisp.html https://www.gnu

I would suggest starting off by reading the first few chapters of the official elisp manual https://www.gnu.org/software/emacs/manual/elisp.html https://www.gnu.org/software/emacs/manual/elisp.html and experimenting as you go along.