Upload an image and save it as an .png file?

How do I upload an image to Adobe Media Server?

Here's what I'm trying to do. I have a sharedObject that I want to store my thumbnail in.

sharedObject = SharedObject.getRemote("thumbnail",mync.uri,false);
sharedObject.client=this;
sharedObject.connect(mync);

Then I get the image and send it

var screenshot:BitmapData = new BitmapData(VD1.width,VD1.height,false);
var encoder:PNGEncoder = new PNGEncoder(); 
var pngByteArray:ByteArray = encoder.encode(screenshot); 
pngByteArray.compress(); 
sharedObject.send("saveThumbnail", pngByteArray);

But this code doesn't do anything. I'm probably going about it the wrong way.

The ActionScript3 reference says that you can:

Store and share data on Flash Media Server. A shared object can store data on the server for other clients to retrieve

However, I don't want other clients to retrieve it. I just want it to be stored on the server as a .png. How can I do this?