Marketpress with Headway 3.0 Issues

Hello!

I am having some issues with the formatting (not sure if this is the correct term) of Marketpress when used in conjunction with Headway Theme 3.0. I'd like to point out that I am a relative beginner when it comes to WordPress, which is the reason I decided to use Headway as my main theme due to the WYSIWYG editor and relative newbie-friendliness.

The issue I'm having is that the Checkout Page seems to not have any formatting and I can't figure out how to edit it using the Headway Theme Editor. I uploaded a couple of pics to try and visualise the issue. The first pic is of the Shopping Cart and Product Categories widgets with the start of a Product Category list displaying below them. The second pic is how the Checkout Page looks after you click "Checkout" on the previous pic, everything seems to be squidged to the left side.

I have been fiddling with Headway's visual editor for quite a while now but can't seem to find a way to fix this. Could anyone please help? While I am a beginner, I should be able to delve into code if I need to with a bit of guidance. Thanks in advance!