There are already hundreds of threads with this question and it's also covered in the FAQ
Please search CSC for answers before posting, also, you need to provide full details and not just a short description (ie current version, target version, HW, etc)
Cisco Unity Connection
Install and Upgrade Guides
http://www.cisco.com/en/US/products/ps6509/prod_installation_guides_list.html
Review reconfiguration guide for target version
Cisco Unified Communications Manager (CallManager)
Install and Upgrade Guides
http://www.cisco.com/en/US/products/sw/voicesw/ps556/prod_installation_guides_list.html
I assume you've already checked the HW compatibility, if not, just search CSC and you'll find all the links or review the FAQ for the CUCM info.
HTH
java
if this helps, please rate
www.cisco.com/go/pdihelpdesk
HTH
java
if this helps, please rate