Check it out on the training level :) But basically you throw 3 thunder clouds and then after a certain distance they'll stop and do a bolt of lightning straight down, with the middle cloud being the strongest.
It can happen if for some reason the connection to your GPU is lost. The game is using 3D acceleration to improve performance. Check here : http://helpx.adobe.com/x-productkb/multi/stage3d-unsupported-chipsets-drivers-flash.html If your GPU doesn't support Stage 3D then it will tell you at the bottom. Make sure to have the latest GPU drivers and the latest Flash. Hope this helps!
WarLight shares some similarities to Risk, but it's quite a different game. The combat, cards, and move order system are completely different.