It very depends on how many custom fields you have, how many default miniBB fields etc. Accordingly to manual:
For viewing new or custom fields on User Info page, you need to set corresponding $l_usrInfo variable. Keys of this array are the same as keys for table fields (for example, if key for user_icq is 5, ICQ language definition is $l_usrInfo). user_custom1, user_custom2, user_custom3 database fields can be displayed on the user info page as well you will need to add corresponding values for these to the language pack though: $l_usrInfo, $l_usrInfo and $l_usrInfo ,- accordingly. You may also add additional custom fields, naming them so they contain 'user_custom' in the system key definition. In that case, set corresponding $l_usrInfo so it begins from 15. For example, if you have 'user_custom1', 'user_custom2', 'user_custom_name', 'user_custom_surname' listed in order one by one, $l_usrInfo keys are 12, 13, 14, 15.