It depends on what you want to develop. If it's web applications then PHP is your best option (the wealth of information, ease of coding in it, server support for it, etc). So just choose a language to learn that suits the needs of what you want to develop/the area you want to work in. If it's PHP though, first start by learning HTML, CSS and JavaScript.
I recommend PHP for anything web related. The book that got me started is called "PHP and MySQL web development", there is a Roman aqueduct on the cover. Highly recommended.
I know PHP, JAVA and ASP.net so I'll base my answer on that. PHP is easier to learn. It is faster than JAVA and ASP.net. BUT less secure than the other 2. You can start from here if you like to learn PHP. http://php.about.com/od/learnphp/a/Learn-Php-In-8-Weeks.htm
Did you just say that PHP is less secure than JAVA? Any programming language can be made secure - the benefit of PHP is that it rarely effects any other stuff on the computer if a programmer fucks up the code - of course, it might leave open databases, and if the webserver is set up to allow eval() and other potentially damaging functions, go right ahead and taker her down. But... yeah. Any language can be made secure, and that goes for PHP as well. Major websites run off of PHP-based code, and does so quite happily, actually. JAVA is ... well. Just, don't go there. Hopefully, at least JAVA on the web will die a quiet death soon enough. Granted, people learn differently, but what got me started with PHP was the need to do some simple pulling and storing stuff in a database. I just looked up how to do that, and started coding. Back then, I had basic knowledge of HTML and CSS, but no real, practical coding experience. Then, I got a few admin-positions in volunteer organisations, and started creating CMSes and such for their web-needs. It just built on whatever I needed to do then and there, and I looked up functions, Googled solutions to similar problems, and learned that way. I have several PHP-books on the shelf, including some O'Reillys, and others, but I think I've maybe opened them once or twice, when my Internet has been down.
It also depends whether you want to work on your own or get employed. I work in a bank and we have like dozens of web applications, none of which (afaik) is in PHP, but several are in ASP .NET. But if you like to create websites on your own, PHP is the way to go.
I would like to suggest PHP which is simple,easy to learn and understand when complare to ASP and C#. After learning PHP you can move further like joomla,drupal,wordpress. Career options are more for PHP.
I wouldn't say career options are higher for PHP than ASP or C# - the latter are often used in larger corporations, public webportals etc., and if you learn C#, you can also create in-house systems running on stand-alone computers, no need for webservers or anything like that - I'd say that PHP is good to know, but not really a career-boost - I very, very rarely see webdev-companies advertising for PHP-knowledge, it's usually .NET, ASP, specific platforms like Drupal or Joomla etc. (which, of course, granted, assumes some knowledge of PHP), not to mention general programming jobs where C-in-some-form is requested.
It depends what you are aiming to do. Are you wanting to create web applications or desktop applications. What will be the functions of these programs. C# is a great choice for complex desktop applications, and for web design Javascript and PHP are your best options.
"I wouldn't say career options are higher for PHP than ASP or C#" The thing here is I find there are "more" jobs looking for php skills, but the .net jobs can pay more (sometime lots more). Don't forget Coldfusion. Not many use this, but I find developing in Coldfusion is fast and easy
There is quite a big difference between a "job" and a "career". There are LOTS of small jobs involving PHP - they pay (mostly) crap, and are often limited to smaller projects. At least that's my experience. Most larger projects are not made with PHP, but uses other technology, sometimes in combination with PHP, granted, but usually using some other underlaying language.