How to create Pupup Message according to the CLAIMDATE?

Question

   Dear All,

           I would have to implement the Claimdt Concepts for the purchase Order.According to the CLAIMDT Column, i need to popup the message for the users.

           This Should popup before 2 or 1 month of the actual claim Date..


    I have included the Data in excel ..I need query as well as i need popup coding.

   For Example :          Purchasedt         Claimdt 
                   
                               20/7/2013                     20/7/2014