коллеги, кто нибудь пробовал делать
<form id="form1" runat="server">
<div>
<asp:FileUpload ID="uploadedfile" runat="server" /><br />
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click"
Text="Upload File" />&nbsp;<br />
<br />
<asp:Label ID="Label1" runat="server"></asp:Label></div>
</form>

т.е. выбор файла и кнопку "Upload File"
на одной html-странице (1)


а обработку полученного на сервер файла процедурой
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If IsPostBack Then
Dim path As String = Server.MapPath("~/UploadedImages/")
Dim fileOK As Boolean = False
If uploadedfile.HasFile Then
Dim fileExtension As String
fileExtension = System.IO.Path.GetExtension(uploadedfile.FileName).ToLower()
Dim allowedExtensions As String() = {".jpg", ".jpeg", ".png", ".gif"}
For i As Integer = 0 To allowedExtensions.Length — 1
If fileExtension = allowedExtensions(i) Then
fileOK = True
End If
Next
If fileOK Then
Try
uploadedfile.PostedFile.SaveAs(path & uploadedfile.FileName)
Label1.Text = "File uploaded!"
Catch ex As Exception
Label1.Text = "File could not be uploaded."
End Try
Else
Label1.Text = "Cannot accept files of this type."
End If
End If
End If
End Sub




на другой html-странице (2) ??

Как это реализовать?

Поищи по Cross-page posting

Пример (не относится к твоему):
Page 1:
<asp:Button Text="Test" PostBackUrl="PageTwo.aspx" RunAt="server" />
Page 2:
<%@ PreviousPageType TypeName="ASP.PageOne.aspx" %>
void Page_Load (Object sender, EventArgs e) {
TextBox input = (TextBox) PreviousPage.FindControl ("Input"); Output.Text = "Hello, " + input.Text;
}