The folders that you use for downloading, sharing etc are listed in the Tools -> options

then in the saving and shared options.

The folders listed are the ones created by default by Limewire (they folders should ne the same). You can create your own folders, wherever you want on your computer, and then list them here - I have one folder for downloads and another for uploads (my "shared" folder). Doing this gives me a chance to check the files before sharing them. Some people have the same folder for downloads and for sharing (this is the default option created by LW).

Hope this helps.