HTML is purely for displaying output to a browser. It is the structure of the page. In a sense HTML is not a programming language.
I would advise that you take a look around at places as mentioned such as the php manual as well as
http://www.phpbuilder.com/ which has some good tutorials/articles.
As you have a C++ background I would not think it necessary to do a college course as you already have an understanding of programming. Ensure that from the outset that you have a good understanding of security within your application. Unlike C++ memory management is not so much a problem as the zend engine (if I remember correctly it is the zend engine rather than the php engine) handles the memory management for you. Take a read of blogs such as Chris Shiflett's blog. He is somewhat of a security buff with regards to php
http://shiflett.org/ .