How do I use a text area field in the form designer

If you wish to use a text area input type for some custom fields you need to set those fields to store more than the default 255 characters. Once you do that the field will show as a text area in the add user and edit user pages of the control panel and you will also see the text area opton in the designer. See the following article which explains how to change the size of custom fields.

Increasing the size of a custom field