Under Button Click event
You have Set Session Variable like
protected void Button1_Click(object sender, EventArgs e)
{
Session["var"]="Value";
Response.Redirect("details.aspx");
}
In details.aspx
Under Pageload you can get the session like
protected void Page_Load(object sender, EventArgs e)
{
string str=session["var"].tostring()
}
Hope it will help you