Installation missing style.css stylesheet.

Just purchased the Highend Wp Theme and when I tried to install this is what I got:

Installing Theme from uploaded file: highend-ultimate-multi-purpose-wordpress-theme.zip
Unpacking the package…

Installing the theme…

The package could not be installed. The theme is missing the style.css stylesheet.

Theme install failed.

**** this was suppose to be a simple process…your assistance will be greatly appreciated.