Add Image to Sub Menu Item in ASP.Net

born59died60 says:

but there should be no image for the main menu, only submenu items

In order to display the image for submenu items you need to set the MenuItem Text property with Image only for the ChildItems i.e. parentMenuId not equal to 0.

Private Sub PopulateMenu(dt As DataTable, parentMenuId As Integer, parentMenuItem As MenuItem)
    Dim currentPage As String = Path.GetFileName(Request.Url.AbsolutePath)
    For Each row As DataRow In dt.Rows
        Dim menuItem As New MenuItem() With {
            .Value = row("MenuId").ToString(),
            .Text = row("Title").ToString(),
            .NavigateUrl = row("Url").ToString(),
            .Selected = row("Url").ToString().EndsWith(currentPage, StringComparison.CurrentCultureIgnoreCase)
        }

        If parentMenuId = 0 Then
            Menu1.Items.Add(menuItem)
            Dim dtChild As DataTable = Me.GetData(Integer.Parse(menuItem.Value))
            PopulateMenu(dtChild, Integer.Parse(menuItem.Value), menuItem)
        Else
            menuItem.Text = "<a href='MenuMasterSide.master?menuid=" & row("MenuId").ToString() & "'><img src='images/orange_square.png'></a>" & "  " & row("Title").ToString()
            parentMenuItem.ChildItems.Add(menuItem)
        End If
    Next
End Sub