Conversion with custom trackevent


I have following piwik custom click event code for my slider

_paq.push([‘trackEvent’, ‘product_id’, ‘SliderName’, ‘userID’]);

I am getting slider name , product_id and UserId in Database.

How can i track following above click ecommerce order placed or not ?

i want to find out click to conversions with different sliders.

currently using piwik version.