CIDX and R/3

I have a senario is like this

INBOUND

I am getting CIDX Standard document which is ORDRS CREATE to XI system and Convert or MAP that document to IDOC which is ORDERS05, send to R/3 system.

OUTBOUND

and same senario from R/3 to XI and XI to CIDX standard document.

to fill this requirement do we need to get the authentication for using the CIDX adopter.

Where exactly i have to import the XML schema into XI system to map the IDOC structure.

I have seen couple of examples which they are telling menction the CIDX adopter in communication channel which is configuration part (IB). Before that we have to do the mapping. Can any body please explain the process needs to be done.

Thanks

M