User blog comment:Underscorre/Blank Pages/@comment-25755652-20150516132801/@comment-25428589-20150516135436

First, ensure you're editing in source mode. You can do this by going to Special:Preferences and changing your preferred editor to "source editor".

Next, go to the bottom of the page you want to attribute, and add the following code to it: "" (without the quotes), replacing username with the name of the author. Hit publish, and the "by" thing should be added.