How do we access viewstate value of this page in the next page ?

View state is page specific; it contains information about controls embedded on the particular
page. ASP.NET 2.0 resolves this by embedding a hidden input field name, __POSTBACK. This
field is embedded only when there is an IButtonControl on the page and its PostBackUrl property
is set to a non-null value. This field contains the view state information of the poster page. To
access the view state of the poster page, you can use the new PreviousPage property of the page:
Page poster = this.PreviousPage;

Label posterLabel = poster.findControl("myLabel");
string lbl = posterLabel.Text;

This cross-page post back feature also solves the problem of posting a Form to multiple pages,because each control, in theory, can point to different post back URL.