want grid instead of list for product page

Using the Marketpress plugin on my theme. The products category page put everything in a list. I want it to be a gallery grid of thumbnails. I've cruised through many questions and answers for this in here and have not seen the solution.

There was one that said to create a new theme in the marketpress-includes/themes folder. So, I copied the classic, renamed it and am trying to edit it to do this. But I'm not a code master. In that theme where is the section about the product list page and how do I change it to make that page load in a grid format instead of the list format?

Some answers say to use the gridmarket theme. Well, that would mean to completely edit that theme to look like the theme I already have. Too much work.

Is it possible to just add code to my changed classic theme in the marketpress plugin to make the product pages open in a grid format without all the product text info? If so, what code would do that?

And I'm curious, why wasn't the plugin made so that the product pages would be in a grid to start with? Isn't that what most people want?

Thank you so much for your assistance! Other than this grid issue, this looks to be the most fantastic e-commerce plugin out there.

Dee