The following KB articles relate to this topic:
The image gallery content block can be used to display a large amount of images on the page. Images will appear as thumbnails until clicked. Once clicked, a larger version of the image will pop up, as well as a short description of the image. (The image description does not appear on the thumbnail version). Once the gallery is opened, users can peruse the images by clicking the arrow buttons or by using the arrow keys on their keyboard. To exit the gallery, users need only click the 'x' in the top right corner of their screen.