Hi Raj,
It depends on what scenario you have,
1. Ariba Integration using Network Adapter then use the above link by Jens and install the ESR content and map outbound proxy with ESR cotent.
2. Ariba Integration without Network adapter develop your mappings to generate the putput stucture with cXML tag
3. Any other third party integration for cXML exchange then check if you have ESR content available and if not then develop mappings to transform it to cXML structure.
Let us know more in details if you have any other question.
Regards,
Nitin Patil