You need to create a new category template. Look in templates/categories. Maybe copy the ProductsInGrid and then manipulate it the way you need.
Basically you need to create a new user control and add then register the new template in the Nop_CategoryTemplate table in the database or through Content Management -> Templates - > Category Templates.
I changed the file: \Templates\Categories\ProductsInGrid.ascx
And I changed the repeat columns to 3 which is exactly what I wanted.
Now I have the problem that the 3 boxes that contain the product images are in 1 row but they extend and overflow across the right side of the content section which I don't want.
Is it possible to make it such that regardless of how many repeat columns that they will always be relative to and contained within the content section ?
I have made two changes in the category.css file in the the app_themes, nop classic folder That is namely changing the addinfo and product item width from 250px to 150px and leaving the ProductGrid width at 550. Since I have repeatcolumns set to 3 it should be less than 550.
When I do that in firebug to get a quick preview it works. Then when I modified the category.css file and uploaded it to my hosting web server and come back to my site it still is having the same problem.
When I check in firebug it says the width is 250px, but when I download the file again from hosting site it says 150px which is strange.
Could there be any reason for this or am I making incorrect changes?
Just confused at the moment. Any help would be appreciated.