I assume you want new headers on a report. Any report in particular?
If you just want to change the company details on a header report, just configure it on the Company Information window (Tools | Setup | Company | Company).
If you need specifics like adding a logo, you need to do this in Report Writer. The graphic file needs to be a maximum of 32KB. You can check the link below regarding this:
www.tek-tips.com/viewthread.cfm
If you want more specific information on adding details to a report header, you may want to check with your MS Partner on assisting you on modifying the report.