How debit works and when it should be used

How debit note works, and when we should use it.
Pls give me some examples of when we can use it

See the Guide at http://guides.manager.io/businesses/debit-notes. An example would be that you return goods to a supplier and, rather than refund your money, they credit your account. That would result in a credit note on your supplier’s books, but a debit note on yours. Since the debit note information in the Guide is minimal, see http://guides.manager.io/businesses/credit-notes for an explanation from the other end of the transaction.