After expanding the zip file, drag each of these folders into your themes folder.

ck_rollover_red
ck_rollover_grey
ck_rollover_brown
ck_rollover_green
ck_rollover_blue
ck_rollover_colorful
ck_rollover_orange


If you don't know how to install a theme, read the documentation at http://docs.moodle.org/en/Themes#Installing_a_theme.