You can manage Custom Fields through the Admin menu (click the cogwheel upper right hand side of Mautic).
The Custom Fields page will let you view all existing Contact fields as well as any custom contact fields you have created.
You will notice the group column which will show you where the specific field will be shown on the Contact profile. In the last column, you may see several icons which signify various properties of the field:
There is a toggle switch which shows before each label title.\ This type of switch is used throughout the Mautic UI to publish and unpublish items.
You can create additional custom fields and define the data type you want that field to hold. In addition to the data type you will also select the group for that particular field. This will define where the field displays on the Contact edit and detail view.
Found errors? Think you can improve this documentation? edit this page on Github