How to add attachments for Activity Header and for partners?

Hi Consultants,

I am new to CRM, My requirement is I have to add attachments as URL and File in activity or lead in Salespro. I have observed from CRMD_ORDER_MAINTAIN but no break-point triggers for this. I searched and found that cl_crm_documents->create_url or some methods in that. But it does not works for me.
Any sample code expecting to reach my object.

Thanks & Regards

Mithuunn,