Rajat,
When you connect to Hadoop from Spoon, it will attempt to connect to the cluster using the user profile of whoever started Spoon. So for example, in my case if I start Spoon in Windows using my 'ceicher' profile, I must have a /user/ceicher directory in the Hadoop cluster, or else I will get similar errors to what you're seeing now.
Further, you'll need to make sure you've configured your Spoon's shim with all the correct *-site.xml files.
Finally, if you have any kerberos security enabled, you'll need to configure that in the shim as well.
-Chris