When you download/upgrade LimeWire, it sets a default Shared Folder. On Mac, I think it's in Preferences. What you should do is:

Go to Tools and choose: Options (a new window will open)

Click on Sharing. This will show you where the Shared Folder is. I believe LimeWire also downloads to this folder. (Make note of the location)

Click once on this folder (to hightlight it) and click Remove.

Click Add and browse to find the folder you want to share and click Select.

You should also go to Saving and change the folder there, too. Same way.

Then go to the folder that LimeWire was saving to/sharing (on your Hard Drive, from the Finder) and move the files into the Shared Folder of your choice. Then trash the folder.

When you re-open LimeWire, it will take some time to hash your old and new files. Give it time. They will eventually all show up in your Library.

I hope this all makes sense.

Good luck.