Add a Global.asax file in your project from add new item menu.
In Global.asax handle the following events.
void Application_Start(object sender, EventArgs e)
{
Application["myCount"] = count;
}
void Session_Start(object sender, EventArgs e)
{
count = Convert.ToInt32(Application["myCount"]); Application["myCount"] = count + 1;
}
and in the page load of the page where you want to display the count
add the following code.
a = Convert.ToInt32((Application["myCount"]));
Label1.Text = Convert.ToString(a);
the label will display the count
Remember if you reset the IIS the count will be reset.
So better to store it in database and get the data from backend and increment for every session creation and then save it in to database.