What do you mean? What are you using for upload?

It depends on the classes you use for uploading your data. You might want to look into the QNetworkReply::uploadProgress() [doc.qt.nokia.com] signal and connect it to the progressbar.

If you use a file you might want to use this:
sendProgress->setValue( (fileToSend->pos() * 100) / fileToSend->size());
The pos() functions comes from the QIODevice class, but it is inherited by QFile.