Customs Communication process

Hello Experts,

I have  requirement to set up to new "message" configuration in Customs communication process.

please provide the step by step to follow the process.

E.g.  from US to DE.

Total 4 messages e.g. XINV, XSED,etc..should be triggered from GTS.

Note: I have gone through the below steps. but need more info and understand of the process. please explain with detailed if possible.

the "messages" should trigger once the customs declaration creates at GTS.

would like to know where this set up need to be done (config/master data setup?)

                                   Thanks in advance!

Thanks & Regards,

Pradeep