' Specify the customer ID. 
Dim contactID As Integer = 4332

Using context As New AdventureWorksEntities()
    context.ContextOptions.LazyLoadingEnabled = False

    ' Get a specified customer by contact ID. 
    Dim contact = (From c In context.Contacts
        Where c.ContactID = contactID
        Select c).First()

    ' Load the orders for the customer explicitly. 
    If Not contact.SalesOrderHeaders.IsLoaded Then
        contact.SalesOrderHeaders.Load()
    End If

    For Each order As SalesOrderHeader In contact.SalesOrderHeaders
        ' Load the items for the order if not already loaded. 
        If Not order.SalesOrderDetails.IsLoaded Then
            order.SalesOrderDetails.Load()
        End If

        Console.WriteLine(String.Format("PO Number: {0}", order.PurchaseOrderNumber))
        Console.WriteLine(String.Format("Order Date: {0}", order.OrderDate.ToString()))
        Console.WriteLine("Order items:")
        For Each item As SalesOrderDetail In order.SalesOrderDetails
            Console.WriteLine(String.Format("Product: {0} Quantity: {1}", _
                                              item.ProductID.ToString(), item.OrderQty.ToString()))
        Next
    Next
End Using