Sorry I know very little about HTML/CSS/PHP but this is what I did to do the same thing you mention.
1) Go to Propulsion/Config-Woocommerce/config.php
2) Delete Line 91 remove_action( 'woocommerce_product_tabs', 'woocommerce_product_description_tab', 10 );
You now have the description in two locations. I just wanted the excerpt and not description listed twice and so I also deleted the following:
1) Line 89 remove_action( 'woocommerce_single_product_summary', 'woocommerce_template_single_excerpt', 20, 2);
2) Line 131 add_action( 'woocommerce_single_product_summary', 'avia_woocommerce_template_single_excerpt', 10, 2);
So far it has been working no issues.