If you just want to link to a profile then create a new text field within CB > Field Management. Once done use a Delimiter field to actually display it using the below.
Code:
[cb:if FIELD_NAME!=""]<a href="http://www.facebook.com/profile.php?id=[FIELD_NAME]" target="_blank">My Facebook Profile</a>[/cb:if]
Replace FIELD_NAME with the actual name of your field (e.g. cb_facebookid).