First, find the item you want to add an alteration
If the item is already open click the "Annotations" tab
If the item isn't open click on the item and then click open then click the "Annotations" tab
Select Damage
Click on the image where the Damage is
Choose what type of Damage was done
Set the price
Select "Unrepaired" if it hasn't been repaired or click "Permanent" if it's a permanent damage
Click Save on the damage
Save the item