Hi May,
For adding in fine tuning you have to add BC set based on your custom BCO. then you can add BC set as a data type in your BO definition.
After creating and activating BC set on BCO you can check in your custom BO using code completion.
For understanding Business Configuration thing I would suggest to read SDK document 1402 at page 280.
In my word Business configuration content know as BAC element in SDK is an important element which must contain at leas an business option, and later after deployment of Business configuration you can see the question created by you during scoping, after reviewing that question your solution would be activated for the business use in productive tenant.
Please let me know if more information needed.
Thanks
Sunil