Change the order of left and right

Hey team,

I wish you’re all good!

I’m now using the Coupon theme. I want to change the sider bar (Store introduce part) to the left, of this page: https://www.iactivation.net/store/tidebuy/

All I need do is to put the codes of side bar at the front of the main part, but the question is which .php file should I edit? I cannot find the exactly .php file of this page.

Thank you in advance for your help!

John