There is an easy way to get a report for information using Drag and Relate in SAP B1.
On the main menu choose Drag and Relate:
Go to Modules-->Business Partners-->Business Partner Master data and open the BP that you want.
Then click and drag the BP number over to the Sales Order menu and let go.
This will create a report of all sales orders for this business partner. You can filter it by clicking on the filter button in the bottom right of this window.
Now, this will only work for things that are related. You can't drag and relate this BP to Item Master data.