How could i setup affiliate rate in percent

You are posting on support forum for the wrong plugin. You should likely use https://wordpress.org/support/plugin/affiliates/ instead. Also if that is what you’re using, then have a look at the documentation http://docs.itthinx.com/document/affiliates/ where you can find details on the integration with WooCommerce http://docs.itthinx.com/document/affiliates/setup/settings/integrations/woocommerce/