You are almost there, look at this code, should get you over this hurdle
😎
SELECT
SDH.SalesOrderID AS '@SalesOrderID'
,(SELECT
SD.OrderQty AS 'Product/@OrderQty'
,SD.CarrierTrackingNumber AS 'Product/ProductID/SalesOrderDetailID/@CarrierTrackingNumber'
,SD.ProductID AS 'Product/ProductID'
,SD. SalesOrderDetailID AS 'Product/ProductID/SalesOrderDetailID'
FROM Sales.SalesOrderDetail SD
WHERE SD.SalesOrderID = SDH.SalesOrderID
FOR XML PATH(''),TYPE) AS Products
FROM Sales.SalesOrderHeader SDH
WHERE SDH.SalesOrderID = 44115
FOR XML PATH('SalesOrder'),TYPE, ROOT('SalesOrders');
Result
<SalesOrders>
<SalesOrder SalesOrderID="44115">
<Products>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />777<SalesOrderDetailID>1815</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="1">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />747<SalesOrderDetailID>1816</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="1">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />743<SalesOrderDetailID>1817</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="3">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />707<SalesOrderDetailID>1818</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="1">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />708<SalesOrderDetailID>1819</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="3">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />775<SalesOrderDetailID>1820</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />771<SalesOrderDetailID>1821</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />716<SalesOrderDetailID>1822</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="7">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />774<SalesOrderDetailID>1823</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="1">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />748<SalesOrderDetailID>1824</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="4">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />778<SalesOrderDetailID>1825</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="3">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />742<SalesOrderDetailID>1826</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />712<SalesOrderDetailID>1827</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />773<SalesOrderDetailID>1828</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />741<SalesOrderDetailID>1829</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />711<SalesOrderDetailID>1830</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="9">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />772<SalesOrderDetailID>1831</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />745<SalesOrderDetailID>1832</SalesOrderDetailID></ProductID>
</Product>
<Product OrderQty="2">
<ProductID>
<SalesOrderDetailID CarrierTrackingNumber="5360-4C42-90" />714<SalesOrderDetailID>1833</SalesOrderDetailID></ProductID>
</Product>
</Products>
</SalesOrder>
</SalesOrders>