Put some pictures on the page and size them to be a nice thumbnail size.

I dropped all eight of these pictures from my windows file explorer.  I set each one of them to be 125 pixels high so that they are all exactly the same size

Click on each image so that the Image Properties sheet is in the right sidebar as seen in the image below.

Set the Link To property to Source Picture which is done by default. 

As you can see, the picture will be 640x480 when you hover over and click the thumbnail.  If you wish this to be a different size, press that options button and set as desired.

Click on the advanced Tab and put in a nice little Search Engine Friendly caption for each picture.

Publish and you have a simple photo gallery

You could also hide a photo gallery in a footnote.¹

This picture hides a gallery. 
²