INPUT id="File1" type="file" name="File1" runat="server">
asp:Button id="Button1" runat="server" Text="Button">/asp:Button>
asp:DataGrid id="DataGrid1" runat="server">/asp:DataGrid>

string strPath="c://test//" + DateTime.Now.ToString("yyyyMMddhhmmss") + ".xls";

File1.PostedFile.SaveAs(strPath);

string mystring="Provider = Microsoft.Jet.OLEDB.4.0 ; Data Source = '"+ strPath +"';Extended Properties=Excel 8.0";

OleDbConnection cnnxls = new OleDbConnection (mystring);

OleDbDataAdapter myDa =new OleDbDataAdapter("select * from [Sheet1$]",cnnxls);

DataSet myDs =new DataSet();

myDa.Fill(myDs);

DataGrid1.DataSource=myDs.Tables[0];

DataGrid1.DataBind();