How do I make my accounts or contacts PRIVATE - so employees dont see them?

How do I make my accounts or contacts PRIVATE - so employees dont see them?

How do I make my accounts or contacts PRIVATE - so employees don't see them?
I would like to add Vendors to my account  but I DO NOT WANT MY EMPLOYEES TO SEE THEM.  is there a way to mark them private so no one else can see them?

Thanks
Christine