Put twittering-mode.el in a directory specified by the variable load-path. Note that the directories emacs21 and url-emacs21 must be placed at the same directory on Emacs 21. On Windows without curl or wget, the directory win-curl must be placed there. You can add a directory to the variable load-path by (add-to-list 'load-path "ADDITIONAL-DIRECTORY"). Execute M-x twit to run twittering-mode. Open