LEDE Firewall - How to Prevent Skype

Installing and Using OpenWrt
1

I would like to block and/or schedule skype usage on my home LAN for specific MAC adresses using this method

http://www.ilsistemista.net/index.php/howto/32-how-to-block-skype-connections-with-your-gateway-firewall.html?limitstart=0

My networking skills are basic at best so if you want to help, please do not assume any prerequisite knowledge.

EDIT: I do use the web based GUI, not terminal.