NZFF

I'm wanting to get started on some payware scenery for FSX. I'm a PHP and .NET programmer by hobby so I'm competent with computers.

How does one get started with scenery in FSX though?

Install the SDK first, it has some tools which you can't really do without.
The best source of info is FSDeveloper.com, spend a month browsing the forums and you'll get a good idea of what is needed. Since this question is asked there at least twice a week, there are some very helpful 'getting started' discussions.