How to modify layout in Checkout ?

Hi, I am a beginner of opencart. The current layout in the opencart is using panel to allow customer to fill in details and shipment. I was thinking to modify the layout but I don't know how to remove the panel and the unnecessary panel in the checkout page. Is there any way to do so ? or someone would be nice to help me out here?


I need to change it into 2 column with Contact Details, Select Store, Pickup time and Date on the left and also Order Review on the right side.


Thanks.