Co-Authors Plus on TrueMag

Hi,

I have installed Co-Author Plus on my website in order to allow multiple-author articles.
Unfortunately, although I put more than an author, on the final post only the first name is shown.

I’ve had a look at the forum and apparently there’s some code lines to add on some .php

I’m a wordpress newbie so I don’t really know what to add and where – everything I tried so far has made things worst.

Could you please give me support to make Co-Author work on TrueMag?