Hello Anupam,
1. You need to copy the IOS from CCO.
2. The same IOS needs to copied on to the flash.
#copy tftp : flash
#tftp ip address <x.x.x.x>
3. I would suggest before upgrading the IOS. Please verify the MD5 checksum and confirm with CCO that it matches. This confirms that while copying the image didnt get corrupt.
#verify /md5 Flash:<IOSimage>.bin
4. Once you see the IOS in flash. Please configure below.
boot-start-marker
boot system flash <IOS image name>.bin
boot-end-marker
5. Save the confguration.
#wr
6. reload the router. Post reload you can run " show version" to check if device has come up with new IOS.
HTH,
Nikhil
