LW doesn't upload them automatically; they are downloaded from other Gnutella Network users looking for the files you have allowed to share.
Of course you can stop sharing, though if everyone would do this, then what would you download??
In the end you'll decide which files you want to share and which not.
Go LW>Tools>Options>Shared to add or remove files you want to share or not.
To stop sharing, you can go to LW>Tools>Options>Uploads and make the number of upload slots to "0"........but as I said, if no-one would share you wouldn't be able to download anything......
