How do I view purchase order with need by date ?

1. Login to your SAP Business Network Account (https://supplier.ariba.com)
2. Go to Workbench menu and Customize your workbench
3. Add new tile
   
4. Select Items to ship and click Apply to save the change
5. Click on Items to ship tile
   
6. You may configure filter by puting only Creation Date and click Apply to save the change.
   
7. Now your workbench menu will show Purchase Order with Need by date column

Learn more about customizing workbench in SAP Business Network General Functionality Guide (Steps by steps)