bapi for transfer posting

hi,

I am bapi for (MB1B) transfer posting for movement type 311.

the requirement is to do a select on table rkpf, if kdauf is not initial then process the reservation

item with the movement type 311+E otherwise 311.

call the bapi fm BAPI_GOODSMVT_CREATE to do transfer posting.

i should select the reservation no and item no by doing with module pool programming.

how should i enter these values to the bapi fm.

can anyone solve the problem.

with regards,