To get a dashed horizontal line

<hr style="height :0px; color:Black; border-bottom: 1px dashed #000; " />

Get Previous Page Form Values

To get the previous page form element values follow the steps below

Parent page do a Server.Transfer instead of Response.Redirect

Server.Transfer("ChildPage.aspx", true);

true for preserving the form element values

In the ChildPage.aspx access the values from ParentPage.aspx like thus

((TextBox)(PreviousPage.FindControl("TextBox1"))).Text;