Any user can post links to “trusted” sites like Wowhead, YouTube, etc. Attempting to post other links will not work unless wrapped in a code line like so.
Examplewebsite.com
Furthermore, the new WoW forums have users earn Trust levels by completing various tasks. Right now you are Trust Level 2. Only Trust Level 3 characters can post pictures and all links freely. All of this and more is delineated here. New Forum Guide - Syntax and Features I hope this helps!