What is the procedure to apply discounts?

You can apply the discount in your voucher in two ways
For voucher level you can apply discount in bill sundry
& for item level discount you can use item wise discount
To apply the discount through bill sundry please follow these steps:
Step 1: Go to transactions menu
Step 2: Then create or modify the invoice such as sale,purchase in which you want to apply the discount
Step 3: Then After creating the invoice apply the discount in bill sundry 
Step 4: If discount bill sundry is not found you can create it by pressing f3 key in the bill sundry grid
To apply the discount at item level please follow these steps:
Step 1: Go to administration menu
Step 2: Then click on configuration button
Step 3: Then click on features and option
Step 4: Then click on inventory tab
Step 5: Then select item-wise discount type as simple or compound as required
Step 6: Then save the changes
Step 7: Then go to administration menu again
Step 8: Then click on configuration
Step 9: Then click on voucher series configuration
Step 10: Then select the voucher such as sale,purchase etc after that select the series
Step 11: Then click on voucher configuration 
Step 12: Afterwards select item wise discount option as Y then specify the discount structure as required and save the changes
Step 13: Then go to transaction menu and open the invoice in which you want to apply the discount 
Step 14: Afterwards while creating the invoice whenever you will press enter in item grid it will give you a prompt to apply the discount as per the structure defined by you."