What are you looking to do - set up MS SQL for vCenter? What version of vCenter are you running? Are you looking to migrate you database?

For vSphere 5 here are the links to the approriate documentation -

For installing to SQL - http://pubs.vmware.com/vsphere-50/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-50-install...

For UPgrading or moving a database - http://pubs.vmware.com/vsphere-50/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-50-upgrade...