1. Installing Java
download the java language in your machine from here
2. Downloading IDE
You can use any IDE(integrated development environment) for your comfort like Visual Studio Code or IntelliJ idea, but in our syllabus they teach us in SciTE Editor(extremely old xD) so I recommend using SciTE I know it's old and UI is trash but if you practice in it you can easily program in trash computers of school in board exams ;0