How to upload file with BackgroundTransfer for windows phone

have check the documentation but there is no sample to show how this is done. This is the code for download :

void Download()
{
    btr = new BackgroundTransferRequest(remoteVideoUri, localDownloadUri);
    btr.TransferPreferences = TransferPreferences.AllowCellularAndBattery;
    BackgroundTransferService.A开发者_如何学Cdd(btr);
    btr.TransferProgressChanged += new EventHandler<BackgroundTransferEventArgs>(btr_TransferProgressChanged);
    btr.TransferStatusChanged += new EventHandler<BackgroundTransferEventArgs>(btr_TransferStatusChanged);
}

For upload, can it be done with this backgroudTransfer ? what and how to do it?

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I haven't yet had chance to look at the background transfer stuff in Mango yet, but there is a lab that covers it in the Mango Offline Training Kit: http://msdn.microsoft.com/en-us/WP7MangoTrainingCourse and I do know that it can do uploads as well as downloads.