Google picture…

Hello,
I have a problem, I mean question. I am using a wp platform for my current website. What I want is Google to show on the page where my website appears a picture.
Here's an example:

But I want Google to put there the picture I used for that post. e.g. If on my website is a post regarding lemons and I chose a picture with lemons when I published the post, I want Google to show that image when that post appears on search… If you understand….
Google picture…

See original post by Cicu Alex-Fabian