Please refer to below code what i had written.
lw_bape_prps-wbs_element = lw_wbs1-wbs_element.
lw_bape_prps-customer_id = lw_wbs1-customer_id.
lw_bape_prps-customer_grp = lw_wbs1-customer_group.
lw_bape_prps-customer_geo = lw_wbs1-customer_geo.
lw_extension-structure = 'BAPI_TE_WBS_ELEMENT'.
lw_extension-valuepart1 = lw_bape_prps+0(240).
lw_extension-valuepart2 = lw_bape_prps+240(240).
lw_extension-valuepart3 = lw_bape_prps+240(185).
APPEND lw_extension TO lt_extension.
CLEAR lw_extension.
And the structure 'Bapi_te_wbs_element' contains fields as below
| WBS_ELEMENT | PS_POSID |
| .INCLUDE | CI_PRPS |
| ZGROUP | KOSTL |
| ZSKILL | CHAR40 |
| PO_ITEM | NUMC3 |
| ZDATE1 | ZDATE1 |
| ZDATE2 | ZDATE2 |
| ZDATE3 | ZDATE3 |
| ZDATE4 | ZDATE4 |
| ZDATE5 | ZDATE5 |
| ZFTA | CHAR40 |
| ZDATE6 | ZDATE6 |
| ZCOMP | ZCOMP |
| ZCOUNTRY | ZCOUNTRY |
| ZPROJTYPE | ZPROJTYPE |
| ZPROJTYPE2 | ZPROJTYPE2 |
| ZPROJLEVEL | ZPROJLEVEL |
| ZPROJGRP | ZPROJGRP |
| ZNATURE | ZNATURE |
| ZPROJTYPE3 | ZPROJTYPE3 |
| ZCONRATE | ZCONRATE |
| ZPROJTYPE4 | ZPROJTYPE4 |
| ZIPO | ZIPO |
| ZCUSTGRP | ZCUSTGRP |
| ZREVCOUNTRY | ZREVCOUNTRY |
| ZREVREGION | ZREVREGION |
| ZSOURCE | ZSOURCE |
| ZLOCATION | ZLOC1 |
| CUSTOMER_ID | ZCUSTOMER_ID |
| CUSTOMER_DEC | ZCUSTOMER_DEC |
| CUSTOMER_GRP | ZCUSTOMER_GRP |
| CUSTOMER_GRPDEC | ZCUSTOMER_GRPDEC |
| CUSTOMER_GEO | ZCUSTOMER_GEO |