Using demo content
ZIP file which you downloaded from Themeforest is containing demo installation with all source codes and content including sample images. Note that the images are not same as on the preview server because of image license. Copy the demo folder from the downloaded file into the webroot and rename the directory. In the demo directory you can find database dump named database.sql. Connect to your database server and create database and user. Don't forget to add correct permissions to new user to access the database. After that you need to modify sites/default/settings.php file. You have to set correct database credentials. Locate the $database array and set proper credentials. Now you can import the dump file. For import you can use SequelPro or PhpMyAdmin. Below you can see working example from settings.php.
$databases = array ( 'default' => array ( 'default' => array ( 'database' => 'database_name', 'username' => 'database_user', 'password' => 'database_password', 'host' => '127.0.0.1', 'port' => '', 'driver' => 'mysql', 'prefix' => '', ), ), );
With this type of installation you need realize that you are installing everything from our preview server (instead of images) so don't forget to set proper values for settings as email address, admin password, etc. Use this installation if you want exact copy of our preview installation. One more thing. The login and password is admin and demo.