Creation of Filter - SE18??

Hi All

How can we create a filter (SE18)? Jothi has explained me about BADIs some time ago.. while I am practising I got struck with the creation of filter... Say for ex: How can we create a filter for BADI HRHAP00_DOC_BC?

and also

Re: You have to make use of the BSP Application HAP_DOCUMENT (SE80->BSP Application->HAP_DOCUMENT).

Q: Could you be precise??