OK you should forward a port (open a port) for your router. See HERE (probably best to choose 1st in results.) BUT you must 1st set up a static ip which is explaned in a link on the previous page link (2nd line.) You should use Port 6346

If you should still have problems after this it means your router does not support UPnP so see here: Force IP instructions & sample image

Common Firewall configurations for LW can be found here: http://www.limewire.com/english/content/firewalls.shtml

ALso update your Java: Java 1.5 (take the JRE)