Hey there, This comes up now and then so let us clarify: You don't need to register for the forums, that is for administration use only. It is only possible to post to the forums from your phone/ device and not from pc, (unless you are a mod or support)
I have no problem posting from PC. Here is what you do: Log into your account at kingdomsofwar.com/play and then click forum. You should be logged in if you do that. If not then I guess you're just not one of the lucky ones.