CB Auto Actions is entirely UI based. You configure the action within CB > Plugin Management then click the Auto Actions button in the CB Auto Actions row. You can find some videos below to help get you started.
www.youtube.com/playlist?list=PLp0puRITgC7McQcw0Sli1qfSUQGwmflzi
As for a Code action all it's doing is executing whatever code you supply it. This could be JS, jQuery, PHP, etc.. In the case of JS or jQuery it will output those to the DOM and run as normally if that trigger has a display output and isn't just a PHP operation (the trigger provided above is same one used by CBSubs Promotions to add the coupon input and should work fine for jQuery).