[Theme: Fineliner] Gallery/Portfolio trouble

I’m having a ton of trouble setting up galleries and portfolios. I’m new to WP, but I’ve got a decent understanding of raw HTML & CSS. I had a freelancer set up this theme for a client (contractor/remodeler), but I’m not getting much help and things aren’t working correctly.

I created four portfolio categories and uploaded some photos for the freelancer to start setting up the portfolio pages, thinking once they had been set up, I could add the rest of the images.

Here’s an example of what is going on:
There is a category “Baths”. From the admin module in “Portfolio Items” there are two images in that category, however neither of the thumbnails are displaying with the rest. When I go to the live site and navigate to “Baths”, there are two images displayed, but they are the same photo. When I click on a photo, it goes to a page that says “You have not yet added any images.”.

The beta site is here: https://461.e8f.myftpupload.com/

I’m confused and very frustrated. Would the WP community please help me A) help me understand the basic frame work of how these portfolios & galleries are supposed to work and B) figure out why these aren’t displaying properly.

If there’s a tutorial available on this, please point me to it. I’m having trouble sifting through the thousands of search results to get to what I need.

Thanks.