Drop the theme in a folder that is on `custom-theme-load-path'
and enjoy

or

(load-file "path/to/jazz-theme.el")
(load-theme 'jazz t)

Don't forget that the theme requires Emacs 24+.

The more information on the project page at https://github.com/donderom/jazz-theme

; Credits

Jani Nurminen (zenburn theme for vim)
Bozhidar Batsov (zenburn theme port for Emacs),
Christian Brassat <crshd@mail.com> (jazz theme initial colors inspiration)