Hi Kalpana
In your it_table (internal table) where you store the resultant data, you need to add one more column with length of 25.
Then based on your code,
READ TABLE it_bsik WITH KEY bukrs = it_with_item-bukrs belnr = it_with_item-belnr gjahr = it_with_item-gjahr.
IF sy-subrc = 0.
it_with_item-ebeln = it_bsik-ebeln.
it_with_item-zuonr = it_bsik-zuonr.
CONCATENATE it_bsik-ebeln it_with_item-ebeln INTO it_with_item-your_new_field
SEPARATED BY '-'.
MODIFY it_with_item TRANSPORTING: it_with_item-your_new_field.
ENDIF.
Regards,
Venkat