What is Content Construction Kit (CCK) in Drupal
It used to be called CCK in Drupal prior to Drupal 7, and came in the shape of a contributed module.  In Drupal 7, most of the functionality of the CCK module was moved into the core and it is now usually referred to as "fields" (or "fields in core").

The purpose of the CCK was to provide a simple UI for adding new "fields" to entities so that new, specific content types could be created by site designers.

In Drupal 7, you do exactly the same thing by adding "fields" (which may be typed) to entities.  A full tutorial about CCK/fields is beyond the scope of this Q+A site, but GIYF (Google Is Your Friend).

Edit: As noted in a comment by jimajamma, the CCK project page has more information and links to tutorials.