I mean when someone clicks on the image of the portfolio, it goes to another page. on that page i want to add more photos. it needs to be something like photogallery.
Please take a look into documentation once again more carefully, because we are pretty sure that you missed Link To option which is extremely important.
Comments
to add more photos on single portfolio pages, you can use Wordpress Gallery. More details about WP default gallery you can read on https://codex.wordpress.org/The_WordPress_Gallery
Thanks!