DirectIQ allows you to create your custom field. To do this go to Contacts -> My Fields and click Create Custom Field in the right top corner of the page.
A dialog for creating a new field will open. Enter field name in the text editor, select type from the drop-down list, choose whether the field will be public or private. After this click Save.
If the field type you have selected is Date, then another drop-down list will appear. Here you need to choose in what format the date will be displayed.
After you save the new field, it will appear in the list of all fields.