Once you have installed osCommerce, you can access the store's administration page by clicking "next" at the last step of the installation process, or by clicking the "Configure osCommerce" button on the main screen.
For detailed information on configuring your store, please read the documentation provided by osCommerce.
NOTE: as the osCommerce application in WebsiteOS handles the installation and uninstallation processes, you may safely skip these sections in the manual.