Hi Imran,
it is in same
SAP Reference IMG->Customer Relationship management->CRM Cross-Application Components
->Generic Interaction Layer/Object Layer->component specific seetings->define simple objects.
select your created object and click on relationship tab and fill required details as mentioned. From there you can do it.
And if you want to use Object and Model table then try to check following link
http://harelgilor.blogspot.in/2010/06/sap-crm-how-to-create-your-own-bol.html
Regards,