how to create selections-screens to display PO using module pool program

All,

I'm new to module pool programming. Can any one please provide me where to create selections screens to display existing purchase orders using the below selection criteria in thr module pool program.,

SELECT-OPTIONS : S_LIFNR FOR EKKO-LIFNR,

S_BSART FOR EKKO-BSART,

S_BUKRS FOR EKKO-BUKRS,

S_WERKS FOR EKPO-WERKS OBLIGATORY,

S_BEDAT FOR SY-DATUM,

S_EINDT FOR EKET-EINDT,

S_EBELN FOR EKKO-EBELN,

S_MATNR FOR EKPO-MATNR.

provide me step by step to do this.