Instructions to install a ready-made site in localhost
You need to tell Drupal where the database is that you imported.


Make sure to copy default.settings.php in sites/default to settings.php (if it does not already exist, in which case you can skip this step.).
Edit $databases array (lines 213 or so) in setttings.php. You should add the username and password of a user with full privileges on your MySQL installation (usually it will be user root, with password root).


For instance:

$databases = array (
  'default' =&gt; 
  array (
    'default' =&gt; 
    array (
      'database' =&gt; 'NAME OF DATABASE YOU IMPORTED',
      'username' =&gt; 'USERNAME',
      'password' =&gt; 'PASSWORD',
      'host' =&gt; 'localhost',
      'port' =&gt; '',
      'driver' =&gt; 'mysql',
      'prefix' =&gt; '',
    ),
  ),
);


You should now browse to admin/reports/status which, will give you instructions to change file permissions for settings.php so that it is not publicly writable, and maybe to run Cron or Drupal updates.

Please also look at Migrating a site for more in-depth instructions. 

Chances are that the default root username and password for your MySQL instance would be: root, and root. If it is not, then please open PHPMyAdmin and have a look at the User tab section/or google for assistance on how to create a new user with 'ALL Privileges'.