Hi Ravi,
Would suggest reading this blog below if you are new at PI. Its an excellent read.
http://scn.sap.com/docs/DOC-41766
Now to answer your question - If you are trying to test your mapping it would be on the ESR (Enterprise Service Builder)
1. Open up the Message Mapping.
2. You will need an xml to test the mapping. You can create your own xml in message mapping under test or if you tested the interface by running it from the source i would suggest that you go and get the xml under sxi_monitor. Copy the xml and paste it into the message mapping under test.
3. Now you have data to test the interface
4. You can go onto each field and right click and select display queue. This will run the data into the mapping for that specific field. If there is a problem it will display a dialog box.
5. After fixing all the issues in the mapping. Just save and activate.
6. Then do end-to-end test again.
If you need any additional information just let me know.
Regards,
Jannus Botha