Create an own template

To create an own template, you only have to create a /post-gallery folder in your theme-folder: wp-content/themes/yourTheme/post-gallery

There can you create a new php-file. All image-data is in the variable $images

$images has the following information:

array(1) {
  ["image1.jpg"]=>
  array(7) {
    ["filename"]=>
    string(10) "image1.jpg"
    ["path"]=>
    string(50) "/wp-content/uploads/gallery/myGallery_47/image1.jpg"
    ["url"]=>
    string(86) "http://yourdomain.com/wp-content/uploads/gallery/myGallery_47/image1.jpg"
    ["thumbURL"]=>
    string(107) "http://yourdomain.com/?loadThumb&path=/wp-content/uploads/gallery/myGallery_47/image1.jpg"
    ["title"]=>
    string(0) ""
    ["desc"]=>
    string(0) ""
    ["alt"]=>
    string(0) ""
  }
}

Select own template

There are two ways. First you can set the template global for all posts. The only thing you have to do, is to go in wp-admin under PostGallery and select your new template as global template.

Or you can set it for a single post only. Go in wp-admin in your post. Scroll down to gallery-settings. There can you select your template.