Okay, let me start from scratch, with apologies for my lack of clarity.
Boxer plugin uses a content block which is essentially a box. It uses sets, so like a box-set you'd have a content block set. Then, you'd create page and enter some simple shortcodes there with the box sets you want on the page. You can have quite a few.
Then, in the Content Blocks setting, you create your 'box'. Add the title, image; set the alignment, font, font size, and the block order, etc. Save.
Go to Special Recent Posts website where you'll find information about the shortcodes. Yes, you can set a shortcode to select X number of posts from Y category with or without thumbnail, etc.
That shortcode is placed inside the edit area of the Content Block and saved.
On the page you've created, you can now see the boxes (content blocks) in the desired order, each with the preferred content from the category's posts, such as thumb, title, excerpt, link, etc.