The role(s) that were added under step 1 in 'New Field' will have access to view and edit the data within this field. If the data is sensitive or related to their employment and you do not want the employee to be able to edit this information, you will need to add the field location to the Job & Pay section and remove the 'employee' role from the view. This will still appear in their profile for admins however, not visible to the employee.
Now that you have created fields, field groups, and assigned it to employee profiles you can now fill in the fields with the appropriate data. There are two ways to do this, through the bulk importer or individually through the employee profiles.
The bulk importer will allow you to add in custom fields for employees all at once or mass update existing fields. The first thing you will need to do is do a data export by going to. Reporting > Data Export. This step will export an excel field of all fields in the employee profiles, including the assigned custom fields. Once exported, you can fill in the fields directly on the excel then import it through Company > Import.