Through Resources section on the navigation bar access your Inventory. Look for the Options sign next to the item you want to set low stock alarm, and select Set alarm option.
Alarms window will appear which requires defining conditions which will trigger the alarm. Make sure to define the Warehouse for which you would like to be warned about in the Set alarm for section, especially if you have stored item on several warehouses and bins. Then, enter the stock threshold which will trigger the low stock alarm.
After your stock reach the level defined in the alarm, low stock alarm will appear in the Alarms section located on the right side of the main navigation bar.
Video how to set up low stock alarm HERE.