I was thinking to declare my finacial & emplyement detail....as you said its not help then how i should prepare SOP which can help me to get the visa
Agreed with the advice given above. Don't waste your money / time with an affidavit - you don't need one and it won't strengthen your application. Just provide you bank statement, pay slips, letter from your employer, etc. These are the documents that are important.
Your statement of purpose should cover your plans in Canada (what you plan to do, itinerary, who/what you'll visit). I would recommend you move over to the Visitors section of the forum and read through the discussions there / post your questions there.