You can write in default text editors, but you are not obligated. The more comfortable way is to use editors like Brackets, Atom, Sublime Text or Notepad++. Personally, I recommend Atom. This is developed by GitHub code editor with great plugins support, many linters and code highlighting. You can download Atom from official website: https://atom.io/
Good developers are using for a long time and are happy with. There are other great editors in our big world, please choose the one you like the most. The choice of an editor, like any other tool, is individual and depends on your projects, habits and personal preferences.