What should I write in web config file in asp.net so that my session time is extended. and please tell me the exact location where should I place the code in web config
You can change the amount of time a session can be idle before it is discarded by adjusting the timeout attribute within the Element.
Remember that the timeout value is set in minutes.
*timeout:*Specifies the number of minutes a session can be idle before it is abandoned. The timeout attribute cannot be set to a value that is greater than 525,601 minutes (1 year) for the in-process and state-server modes.
For reference please see http://msdn.microsoft.com/en-us/library/h6bb9cz9(vs.80).aspx