Displaying a new field type "file"

Hello I have created a new field type “file” so that people can upload pictures. Wanna create sort of my own gallery.
I have followed this instructions: https://wpjobmanager.com/document/tutorial-adding-a-salary-field-for-jobs/

I just dont know how to code the array() terms, or if I need to use new WP_query or if another function is needed?

Thank you for your felp

https://wordpress.org/plugins/wp-job-manager/