Adding fields in customer master data

Hi,

I am working on ECC6.0 ,and want to add certain fields to customer master data,like Bank Gurantee details of Customer.

One option,Text in menu bar EXTRAS,using Trx.code XD02/FD02.The same field not finding in Table KNA1 or KNB1.Please suggest me.

Regards,

Nageswar Rao J