Html is disabled because it is a security risk.
Using html a hacker can post malicious code anywhere that a user can type HTML, whether it be signatures, private messages, or any threads, public or private. They then have the ability to steal the username and password of anyone that views their post. They can also post meta refresh codes and redirect your computer to any site that they want to. Hackers usually like to redirect to porno sites.
Those are just the problems that I know about...
You can format text using <span style="color: #660000">BB code </span>with the <span style='font-size: 14pt'><span style='font-size: 11pt'>wysiwyg text editor</span></span> - use the reply button. Please let me know if there is a particular task that you need to convert from html to bb code.
