EDI to 3rd party system

Hi everybody,

We need to send Some delivery Information to a 3r party system which using that will do PGI & create invoice & sends the goods to customers.

I think we can map this through output determination but in the condition in VV21 SH(ship to party ) is coming in default.

so do we need to create a partner function of SH for that system.

Please guide me & if possible give the steps involved in output determination for EDI.

Thanks & regards

Susrikant