How to filter products with custom attributes ?

Hello, I’m using this plugin:https://github.com/dgrundel/woo-product-importer‎, to import a CSV into WooCommerce, it also successfully allows me to assign fields to custom attributes. But how do I filter within those products with custom attributes ?

Any kind help would be greatly appreciated. I am highly stuck & cant find any solution.

Look forward for the help! Thanks in advance to all! Cheers!

http://wordpress.org/extend/plugins/woocommerce/