If you want to play your music through limewire then select the music in the folder you want to play and right click. A drop down menu well appear, select 'Open With' if you don't see limewire in the list of a few programs, than click 'Choose Program' which is located at the bottom of the 'Open With' drop down menu.
When you click 'Choose Program' a new window will appear. There will be 'Recommended Programs' and 'Other Programs' again if limewire is not listed under it then click 'Browse' This will bring you to another window, normally Program Files, and you should find the Limewire folder there, double click it to open and click the Limewire.exe
Once done just click 'ok' and double click your song and it should open with limewire.