Many WordPress developers would like to become WordPress core contributors. To be a WordPress core contributor, You should find the WordPress core track tickets, which required a patch on the https://make.wordpress.org/core/reports/.
Most of the WordPress developers are familiar with git, but the WordPress core patch can be made by svn in general. However, You can make a patch by git by below steps in windows
- Git download and install (https://git-scm.com/download/win)
- Nodejs download and install (https://nodejs.org/en/download/)
- Run the command
git clone git://develop.git.wordpress.org/ wordpress-developin command line. - Run the command `cd wordpress-develop` in command line.
- Run the command ` npm install ` in command line.
- Run the command ` npm run dev ` in command line.
- Install wordpress in the wordpress-develop/src folder and make your changes
- Run the command ` git diff > 30000.diff ` in command line. It will create the 30000.diff file.