Image Plugin – Please Help

I am trying to get images to appear next to the brief introduction of a post on my site, https://www.crystalgamer.com
Please take a look so you know what I mean. Notice that I have no images visible unless you actually click on a post.

I would like an image to appear on the left of the introduction so that you can see it without clicking on the post.
An example of what I am trying to achieve can be found on https://www.nometet.com

I am not sure how to put an image there but I might need to get a specific plugin but I am not sure which one.

I have no idea how to use plugins so please could someone tell me which plugin to use and how to use it.

Many thanks