Dear Vishal / Ashish
I did these steps only...
1. I get the pgAgent.sql script in pgAdmin III directory , I copied that scripts and execute the scripts in my default postgres database.
2. After, I get the jobs icon in our postgres.
3. In that jobs icon I given jobs name,schedule name and steps
In steps tab I given the step name , Enabled, Database name
Kind : SQL , On error is: Fail
Comment : postgres backup
In definition box : I given this command pg_dump postgres “D:\AGBACKUP\AG.sql”
These steps only I did it…