how it works?

You need to do [gallery link="file"].

thanks but it is also not worked for me ??

this is my code

<div class="gallery">
[gallery link="https://127.0.0.1/occ/1//wp-content/uploads/2014/01/IMG_7698.jpg"]
[gallery link="https://127.0.0.1/occ/1//wp-content/uploads/2014/01/IMG_7698.jpg"]
[gallery link="https://127.0.0.1/occ/1//wp-content/uploads/2014/01/IMG_7698.jpg"]
[gallery link="https://127.0.0.1/occ/1//wp-content/uploads/2014/01/IMG_7698.jpg"]
</div>

and this is the front end output

<div class="gallery">
<br>
<br>
<br>
</div>

You do not need to wrap the gallery shortcode in a div with class gallery – that is automatically done for you by the WP gallery shortcode. Also, you literally have to put link=”file” and not substitute in your file names, as that is telling the shortcode to link to the files within the gallery and not link to the attachment page which is the default.

So copy and paste [gallery link="file"] into your page. (You will need to make sure you have images attached to the page for this to work) and then view the page.

On the frontend, the gallery shortcode will output the gallery code inclusing the <div class="gallery"> and all the images that are attached to the page. The FooBox script will then run, find the images inside the gallery container, and make the images open in FooBox lightbox when clicked.

The img IMG_7698.jpg is attached to my page

the frontend output for

[gallery link="https://127.0.0.1/occ/1//wp-content/uploads/2014/01/IMG_7698.jpg"]

is just

so what is the problem?