Getting gallery images larger on landing page once clicked on.

I have created a page simply for displaying an image gallery of my artwork. Using the Jetpack wordpress plugin I’ve got it looking nicely, but once I click on a gallery image to look at it, I’m taken to a new page with an itty bitty image. The image can then be clicked on and brought up into lightbox using the Responsive Lightbox plugin.

My question is, when you click on my gallery image initially and am taken to the image’s page, how do you make THAT image appear larger?? I want to display a larger image with all the necessary info…

Here is the link to the gallery: here

Thanks to all who can help!