Add this to your Emacs init
:
(setq package-archives '(("gnu" . "http://elpa.gnu.org/packages/")
("marmalade" . "http://marmalade-repo.org/packages/")
("melpa" . "http://melpa.milkbox.net/packages/")))
Or C-: enter the the above snippet.
Then M-xpackage-refresh-contents
And try doing what you have stated above.
Easier way seems to be: M-xlist-packages
.