And I love programming in PHP but not
My personal desire is to become a web
developer and start my own web based
company after completion of courses.
These two sentences conflict. Unfortunately, your own web based company (if you want it to be successful that is) will come with more pressure than working for someone else. The joy of working for someone else is that you're usually not directly responsible for company profits. The downside of not working for yourself is that you usually don't directly reap the rewards of company profits.
As you're curious about what you should know in order to pursue developing your own company, why not take a look at some successful startups (such as Greplin or Dropbox)? Maybe take a look at requirements for a developer at Facebook? Chances are that if you can find what technical competencies they're looking for and find similarities, you might want to start looking in that direction.
Of course, if you're looking to provide software services (building websites for others), then maybe look at tech requirements for someone like BlastRadius.
Things you'll definitely want to know to run your own company (if it's a web based company):
- Distributed architecture (working with multiple servers, cloud computing, etc)
- Web server/code/database optimization techniques
- LAMP stack: *nix, Apache (or similar), MySql, Php/Python/etc
You might also want to take a look at relevant frameworks such as Yii, Kohana or CodeIgniter (for the back end) and jQuery, Mootools, Backbone, etc (for front end) if you are wanting to provide website construction services. Using a pre-built framework always helps increase your productivity once you get past the initial learning curve. You could even start submitting patches for one of the projects in an attempt to get your foot in the door as a committer (usually looks pretty good if you're submitting work to known frameworks in your portfolio).
And now on to the business end. How's your business knowledge? Do you have a clear goal of what you want to achieve with your company? Are you up on current business models if you're developing public software? Don't kid yourself.. Running a company (successfully) is just as challenging (if not more so) than learning how to be a solid engineer. If you're not up to speed on the business end, I'd strongly recommend taking a gander at that side of things before starting your own company.