Creating custom fields
From Planfix
Creating custom fields is done in the Account management section under Custom fields > Task fields:
Using the button New field:
When creating a field, you can select which set to create it in:
Once you have created the field, you can add it to the required objects, where it will appear as follows:
You can read more about using fields in objects in this article: Object form.
Important
You can set permissions for a custom field to restrict its visibility to users in your account.
Alternative method for creating a custom field
You can create a custom field directly while creating or editing an object.