JustShop theme has custom post types for Cakes/Portfolio.

FYI: You can find instructions about setting up portfolio here in documentation too.

First → Create Portfolio/Cakes Items. You can go to Cakes/Portfolio → Add New and fill in your entries for each item. See the screenshot below

Second → Setup a page to display those Portfolio/Cakes Items. Create a new page and name it as you like. Then from 'Page Attributes' section, choose 'Page Template'. See the screenshot below

You will find 3 Page templates related to portfolio:

  1. Portfolio One col
  2. Portfolio Two col
  3. Portfolio Three col

As their names explain, the only difference between these page templates is the number of columns for the portfolio items page.