Hi Ali,
Here are the guides to get you started;
Active Directory 2000 Plugin Installation for Cisco CallManager
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a0080094493.shtml
Active Directory and Cisco CallManager Integration Troubleshooting Guide
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00801d3c48.shtml
This chapter focuses on best practices for AD. However, most recommendations and best practices mentioned in this section also apply to the other directory product supported by Cisco Unified CallManager, the Sun/iPlanet Netscape Directory Server.
From this excellent SRND doc;
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a00806e8c04.html#wp1068184
This chapter covers the main design principles for integrating a Cisco IP Communications system based on Cisco Unified CallManager 4.x with a corporate LDAP directory.
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a00806e8c04.html#wp1043057
Hope this helps!
Rob