As administrator you have the ability to add profile fields which the user fill out, to complete their profiles.
Creating Profile Fields
Simply go to WP admin - Users - Profile Fields and you can add custom profile fields.
Profile fields can be grouped into Profile Field Groups. To create a profile field group :
Primary Field Group & Field
There is a primary field group and a primary field. Do not delete these under any circumstances. These are 2 values which are used internally by BuddyPress. The Primary field group is also displayed on BuddyPress registration page that you set at WP admin - Settings - BuddyPRess - Pages - Register ( requires WP Admin - settings - general - anyone can register )
On the members area it displays like the following :