Hi Shruthi,
In 3rd step is done using SELECT statement.
SELECT EXT_LOCNO
FROM CRMM_LOCMAP
INTO local_internal_table
WHERE condition partner_no = lv_partner_no.
Now you will get the desired record into internal table.
Using READ statement get EXT_LOCNO into work area.
Assign work area to EXT_LOCNO
lv_ext_locno = work_area-EXT_LOCNO.