Hello Ozge, 

Some details might be needed in order to fully answer your question, but I will do my best. 

A custom page is not necessarily possible to configure in PSO via the permissions. But you would be able to take certain existing pages and modify the permissions to view information, or the columns displayed in the page.

To do this you will need to set a List in the administration, when creating said list you will see the various pages and objects that can be modified. 

Once the list is created, it can be assigned to a group, which also houses the permissions of the Workbench. 

Lastly you would want to assign the group to the users, which will then make the list configurations and permissions take place. 

Hopefully this answers the question, although if there is additional information, please feel free to let me know.