to change the 'ALL' the theme developer said to .....
> How to I cange gallery data filter All
I need to change All to Total New Zealand.
You may create translation file as explained here http://adventure-tours.themedelight.com/docs/current/#TranslateTheme and create a translation for string "all" as "Total New Zealand" there. In this case you will achieve that.
Less flexible/useful way is to override 'adventure_tours_post_gallery_filter' function ( defined in include/template-function.php file, from line #833 ) in your child theme and replace title for this link right there. But I would not recommend to do it in this way.
can you guide me with this so I can add it to my child theme