How to restrict reports in the WoC

Hi Friends,

     We are in a situation to restrict the views of "Reports " in the specific work centers to certain users.

     For Eg:  Sales persons  have  to be restricted in viewing the CRM  activity reports like (Lead , Opportunity etc....). Only the sales head has to view the reports. Here our case is that , the sales person have to view only their respective Lead or Opportunities.... else others has to be restricted in viewing  other sales person business leads.

   Thanks in Advance

Regards

Vijay M