Adding Thumbnail Image on Search

Hello everyone,

Can anyone please help me add thumbnail image on google search like the one on the left picture below?

Left is my reference, right is my site. 

Thank you in advance,
K

My site: https://ptphotography.squarespace.com/

4 hours ago, Ptphotography said:

Can anyone please help me add thumbnail image on google search like the one on the left picture below?

Your screenshot shows a 'Featured Snippet'. These appear at the top of Google’s search results in order to quickly answer a searcher’s query.

The content that appears inside of a Featured Snippet is automatically pulled from web pages in Google’s index. Your page can appear as a Featured Snippet if it already ranks on Google’s first page for the search term and your content has been optimised for Featured Snippets. You'll find more details in this article: Featured Snippets.