Configuration of databases in XA_Transaction

Hey i am trying to use XA_Transaction to commit changes in multiple databases… I want to know how to configure the databases while in XA_Transactions.
Suppose i make one connection of XA_Transaction type on 1 database then what about the other database???
How do i access tables of other database in the developer.

Its urgent…
Hope you people respond quickly…

Hi Guru’s

Am also having same query,Hope any body send the solution for this…