You can d/load skins via LW. Open LW and go to View>Apply Skins>Get More Skins. It'll take you here:
Lime Wire » Skins Gallery. Just D/l them via LW, and apply them when they're done. Simple.
If you have more questions, post back and give some details of where your having problems.
This thread may help:
Could someone please help me with downloading skins?!