Hi,
I'm not sure I quite understand the steps that you're taking. If you have a file on your Live Desktop that you'd like to edit, you should save it to your local device, make the changes, then upload it to the Live Desktop again (overwriting the existing file if you've kept the same name for the file). Live Mesh does not currently support editing files directly on the Live Desktop (though this is a popular request, and I'd encourage you to add your vote for such a feature to our
Suggestions sticky).
Please let me know if you have any questions, or if I've misunderstood the situation.
Thanks,
Ben.