There are two approaches to installing Drupal Commerce; this recipe covers installing Drupal Commerce on an existing Drupal 7 website.
You will need to download Drupal Commerce from http://drupal.org/project/commerce. Download the most recent recommended release you see that couples with your Drupal 7 website's core version:
You will also require the following modules to allow Drupal Commerce to function:
Ctools: http://drupal.org/project/ctools
Entity API: http://drupal.org/project/entity
Address Field: http://drupal.org/project/addressfield
Now that you're ready, install Drupal Commerce by performing the following steps:
Install the modules that Drupal Commerce depends on, first by copying the preceding module files into your Drupal site's
modulesdirectory,sites/all/modules.Install Drupal Commerce's modules next, by copying the files into the
sites/all/modulesdirectory, so that they appear in thesites/all/modules/commercedirectory.Enable the newly installed Drupal Commerce module in your Drupal site's administration panel (
example.com/admin/modulesif you've installed Drupal Commerce atexample.com), under the Modules navigation option, by ensuring the checkbox to the left-hand side of the module name is checked.Now that Drupal Commerce is installed, a new menu option will appear in the administration navigation at the top of your screen when you are logged in as a user with administration permissions.
Tip
You may need to clear the cache to see this. Navigate to Configuration | Development | Performance in the administration panel to do this.
Drupal Commerce depends on a number of other Drupal modules to function, and by installing and enabling these in your website's administration panel you're on your way to getting your Drupal Commerce store off the ground.
Tip
You can also install the Drupal Commerce modules via Drush (the Drupal Shell) too. For more information on Drush, see http://drupal.org/project/drush.