There are two different methods you can use to apply discounts in Briefcase.
Applying a discount percentage for a client
Where a client is eligible for an overall discount, you can apply the percentage directly on the client screen. If you navigate to the client, on the bottom left of their company screen you'll be able to add a discount percentage in. Simply enter in the number you would like to discount and click out of the field.
Please note: This change will only affect any items applied after the disc
Applying a discount on estimate line items
Alternatively you can also apply a discount on individual line items on an Estimate. You can do this when creating an estimate by selecting the 'Use complex pricing' checkbox when entering line items.
Once the complex pricing columns appear, simply enter in the number you would like to discount and click out of the field.