These four articles are known as the Mini Features.
To customize them, go to Dashboard > Mini Features > Edit
Clicking Edit will bring you to this page:
Change the Title to whatever is relevant to your brand, leave the main content area blank, and proceed below.
Choose a picture to use as the Mini-Features Icon. Make sure it is 32 x 32 pixels or close, otherwise it will appear blurry or distorted.
The Mini-Features Excerpt are the words that show up on the homepage. Choose something that will entice your audience to keep reading.
The Mini-Features URL is the link that will be attached to the “Read More” buttons. Connect it to the full article or page that you just created an excerpt for.
Update, and do the same for the rest of the mini-features. If you would like to display more than four, use the Add New option.