To display a set of images in a gallery, just surround the images, written as Markdown, with the gallery shortcode.
Clicking the image shows the image in lightbox, with the title as the caption (a little Markdown might in the caption might also work).
{% gallery %}
{% endgallery %}
Produces this:
The image’s own titles appear as captions in the lightbox, but not on the page, as it could get too crowded.
Gallery with caption
To set a caption for the gallery as a whole, pass it to the shortcode.
{% gallery "~~Three~~ Two images side by side" %}
{% endgallery %}
Produces:
The gallery’s caption appears on the page. The image’s own captions still appear in the lightbox, just not on the page.