To use it, type M-x list-packages in Emacs. If you use in Emacs<27, you may want to add something like (unless (fboundp 'package-activate-all) (package-initialize)) somewhere in your init file (e.g. ~/.emacs) to make sure your installed packages are activated at startup. Browse the packages Packages are managed through the GNU ELPA repository (see the GNU Emacs project page for clone instructions)