If you would like to change parallax banner, please create image with same size(1920x727), then open css/style.css file and instead of this: http://placehold.it/1920x727 write your parallax image address like: images/yourimage.jpg

If you would like to change name of Category, please open gallery.html file by any html editor and find following code below:

If you would like to add photos with its thumbnail, you should find code below and do it.
For editing big Photo, please write your image address for example: images/imagename.jpg instead of http://placehold.it/570x350 with title (title="Big Photo").
For editing Photo's thumbnail (small image), please write your image address for example: images/imagename.jpg instead of http://placehold.it/370x250 with title (title="Thumbnail").
For editing photos in the category you choose, you should write in the class="element isotope-filter1" ,filter2, filter3 or filter4.