Using Private/Public Keys for encryption in asp.net

I am new to the conept of Encryption using Public/Private keys (I do understand how it works). I have read that it is best to have a separate set of public/private keys for each User Session. However, I haven't come across a concrete working example (my lack of knowledge). How can we use the public/private key concept with asp.net application effectively? Also, when using the public/private keys, does it effect Sessions, QueryString and ViewState since these objects can hold sensitive information?

Thanks in advance.