How to assign a value(populate) a custom field in a PCUI page ?

Hi

I am working in SAP CRM on its web interface PCUI.

I have created a custom field "ZZ_NEWFIELD" through EEWB in Business Partner. It is visible in accounts transaction header (crmm_account).

Now if I create an opportunity for this business partner, I want to fetch the value of "ZZ_NEWFIELD" from BP Master and display it in opportunity(header) transaction.

Can someone tell me how to go about it ? I am novice to BSP applications.

Regards

Vishal