When you need to add staff custom fields you can navigate to the settings on the menu bar and find the staff on top.
Menu Bar >> Settings >> Staff
Under staff, you will find options shown above and talked about in the intro solution.
Let us work on Staff Fields.
When you enter the Staff fields section you will find some pre-made values for the field as necessities in a form. You can use it as it is or customize them according to your school by removing and adding fields and categories.
Click on the bin logo to delete a category on the left side under the category list
Clicking on the '+Add New Category'.
When you add a new category you will get a popup page where you will need to add details like:
and click Submit.
After you have added a category you can start editing or adding new values of the fields in it.
Click '+Add New Field'
In this area add:
Click Submit to save.
You can repeat the same steps to create more fields.