How do I report harassment

I am in a current game, I was asked to apply to a coalition. Then the leader told me who to help, I did so, he then sends me messages cussing me out, then has a buddy back him up,

kicks me out of the coalition which is fine. but then he goes and writes an article cussing me out calling me names and saying he hopes someone kills me actually.

name calling is petty but i can handle it, but threats to someones life, I do not play games with that.

I have screen shots i did not know how to attach them here, I posted it on your facebook, it took me over an hour in here before it would let me create a thread. . But there are the shots along with his user name.