Flato theme download

I am a very new user to WordPress but whilst looking at various themes, I just downloaded and activated a Flato theme.

I now get an error message trying to do anything in WordPress or trying to access our web site:

Warning: require_once(/home/redhubco/public_html/wp-content/themes/flato/option-tree/ot-loader.php) [function.require-once]: failed to open stream: No such file or directory in /home/redhubco/public_html/wp-includes/template.php on line 441

Fatal error: require_once() [function.require]: Failed opening required ‘/home/redhubco/public_html/wp-content/themes/flato/option-tree/ot-loader.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/redhubco/public_html/wp-includes/template.php on line 441

Can anybody help please??

http://www.redhub.co.uk