To enable the SEF functionality in your osCommerce, you need to install a SEF contribution. There are several SEF contributions for osCommerce, but in this tutorial we’ll focus on installing  Ultimate SEO URLs. You can download Ultimate SEO URLs contribution here. The latest version is compatible with osCommerce 2.2 and 2.3.1.

After downloading the .zip archive on your local computer, please extract it in a directory of your choice.