Hi Jitendra,
Declare a structure of type BAPI_TE_REQUISITION_ITEM.
DATA: ls_req_item TYPE BAPI_TE_REQUISITION_ITEM.
ls_req_item-preq_item = '00010'.
ls_req_item-zzedate = '20140910'.
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ls_req_item-zzcurrn = 'USD'.
t_extn_data-structure = 'BAPI_TE_REQUISITION_ITEM'.
t_extn_data+30 = ls_req_item.
append t_extn_data.