First unpack the zip file you've downloaded when you purchased the theme. After you unpacked the zip contents, you will find inside the mediaconsultTheme the following folders:
documentation - contains the theme documentation
mediaconsult - theme files that must be uploaded to your server
mediaconsult_child - a built in starting child theme for customizations
mc-shortcodes.zip - the shortcodes plugin
mc-custom-posts.zip - the portfolio custom posts plugin
The theme can be installed by uploading mediaconsult folder to your server via FTP (we recommend using FileZilla) in wp-content/themes or by zipping the mediaconsult folder and install the zip file via Appearance › Themes › Install Themes tab › Upload
A more detailed installation guide for installing the theme via WordPress dashboard can be found here.
After installing the theme you can activate it as you would activate any other theme from Appearance › Themes.
Please note that all the theme shortcodes are in a separate plugin (mc-shortcodes.zip) and in order to use them you must first install and activate the plugin. The same goes for custom posts (portfolio) - if you want to use this functionality, make sure that you install and activate the mc-custom-posts.zip plugin that comes with the theme package.
Other important features, such as the unlimited sidebars also rely on the Woo Sidebars plugin, so you might want to install and activate this plugin too.