Please copy your Supported .class files to Proper Jdev Home folder Path.
Refer below link for more understanding on Controller Extension.
Hi Chintu ,
Looking at your requirement I can suggest you the below solutions
1. Do You want to change a message, isn't it ?
If it a Message, then you can change it without going to extension of the Controller.
Try this , execute the below query
select * from fnd_new_messages where MESSAGE_TEXT like '%Put here the Message you are trying to alter%'
Get the message Message_name , go to Oracle AOL -> Application Developer -> Messaage - > Query and Change it.
2. If you want to extended the controller, then your extended class should be in Custom Top
Means refer the below lines
oracle.apps.irc.candidateSelfService.webui.EmployeeInfoCO; // Oracle Controller Class
then your custom class should be created as below
Develop your custom controller and copy the class file to the folder located in $JAVA_TOP/XXCUSTTOP/oracle.apps.irc.candidateSelfService.webui.
Bounce the application server and test it.