Thread:ADour/@comment-27530109-20160419093833/@comment-4651179-20161203192326

If their name is displayed on the screen, just click on it. If not, simply type in the address bar "marvel.wikia.com/wiki/User:XXXXXX" (with "XXXXXX" being the user's name)

You'll be taken to their profile page. Below the box that contains all of their information (number of edits, favorite wikis, etc) you'll see a couple of tabs that say "Profile," "Message Wall," "Blog" and "Contributions." Click on "Message Wall" (if you clicked on their name in a discussion thread like this one, it will take you directly to their Message Wall so you won't have to click on it once you're in their profile page)

Then, right below the "Message Wall" tab (which will now be highlighted in white), there are two boxes that say "What's this about?" and "Post a new message to [User]'s wall"

On "Post a new message..." you simply write what you want to say and on "What's this about?" you write some kind of title for the message. Then after you've written it, you just click "Post" and that's it. Message sent.