There are 3 different gallery option in Tattoo Studio.
1) Artists galleries: You can attach images to the artist’s portfolios as described on the help documentation (It’s link is at Appearance->Theme Settings). There isn’t any shortcode for artist portfolios. These galleries are only accessible from portfolio buttons.
2) Image gallery and video gallery on the about us page: You can add images and videos to these galleries from the gallery menu which is on the left side of your wordpress panel. You can’t use these galleries on any other page. They are only available on about us page (about us page template). There isn’t any shortcode for this type of gallery as well.
3) Gallery shortcode: You can create galleries as many as you want and you can add them to any page or post with this gallery shortcode.