We recommend reading the installation documentation of Drupal: https://www.drupal.org/documentation/install.
You can get Thunder by downloading it from https://www.drupal.org/project/thunder. We suggest the usage of composer for downloading thunder and managing your additional modules. See here for a description howto do that. Download the newest release and install it into your web server document root. Now open the URL pointing to the document root, where you will be directed through the installation process.
Configure your database
Now it’s installing...
Configure your site Define a site name and email-address, set admin username and password and configure your regional settings
Install additional modules
Install & configure Google Analytics (optional)
Install & configure IVW Integration (optional)
Install Facebook Instant Articles (optional)
Install & configure Riddle integration (optional)