WordPress.org

1. Download and unpack plugin files to the wp-content/plugins/scategory-permalink directory.
2. Enable sCategory Permalink plugin on your Plugins page in Site Admin.
3. Go to the Options/Permalinks page in Site Admin and use %scategory% option in Custom text field (you can look here for other options). For example you could use /%scategory%/%postname%/.
4. When you move your mouse over category in Categories box the Primary link will appear on the right. Click it to set the category which will be used to generate permalinks. It will be highlighted with bold.

Upgrade

1. Download and unpack plugin files to the wp-content/plugins/scategory-permalink directory.
2. Go to the Options/Permalinks page in Site Admin and click Save Changes to re-generate permalinks.
3. When you move your mouse over category in Categories box the Primary link will appear on the right. Click it to set the category which will be used to generate permalinks. It will be highlighted with bold.