In AdminCP, go to Groups & permissions > User group permissions and find permission for this add-on. Select the view permission for each user group you want to be visible.
edit the template cxf_extra_user_tab_content with any HTML code or script. If you need any help, you can open a support thread on our forum.
additionally, you can add any widget to the menu. Go to Widgets, create a widget, open the existing one, and choose the widget position [cXF] Extra User Tag: above content or [cXF] Extra User Tag: below content.
check the Options and Style properties page for this add-on for extra settings
Q: How to show a widget only to guests or registered members?
A:
open a widget and go to the field Display condition. Add this code:
!$xf.visitor.user_id to show only to guests
$xf.visitor.user_id to show only to registered users
$xf.visitor.isMemberOf([x, y]) to show to more then one user group