Extending Image width to align with text.

Kind greetings,

I was just wondering if it was possible for my images to be the same width as my text. I know that the images are large enough but I cannot seem to get them any larger than what they are on-screen. Is there a certain coding that I would need to use?
Thanks in advanced.
p.s. I’m using the ‘Klean’ theme in case I’m asking in the wrong forum.

Here’s the link to one of my posts where I have this problem:
http://khoifush.com/the-kollaboration