Content type add node reference
Use the References module:


  This project provides D7 versions of the 'Node reference' and 'User
  reference' field types, that were part of the CCK package in D6


or Entity reference:


  Provides a field type that can reference arbitrary entities


or Relation:


  Relation is an API module and storage model for both simple and the
  most complex relations between entities. The module can handle both
  directional and symmetrical relations very well.