can you recommend some sites to read about PHP coding?
http://www.w3schools.com/ is a good place to start. If you have any grasp about the basic structure of some programming language, it's just a matter of learning some new functions. w3schools doesn't just give a primer about php, but also html, css, javascript and lots more.
The DO's
htlm/css/js: client side programming a must to know what's going on with "your browser". A good read of RFC relevant to http and ssl/tls very useful too to get a hold of how your browser and a web server "talk"...
php: very useful to familiarize yourself with server-side coding. I already heard the song it gives you "bad habits" according to some nazi coders. Irrelevant objection, look at how many websites are coded in php. Facebook is coded in php and with the hip-hop compiler FB gladly released for free you can even compile "real executables" to execute as CGI. So PHP is definitely a must IMO.
Curl: you'll never stop learning how the http protocol and the web in general work with it
VBS (not vbs.net, plain old vbs aka wsh). If you're sticking with windows you'll hardly find a more messy, less elegant, more stupid (well batch?), more deadbrain language. So why am I suggesting it? Because it can do a shitload of stuff relatively decently, it can interact with ActiveX objects in 2 lines, it can be used to work with web pages, it can even be compiled with 3rd party apps readily available on the net. You don't need to be a 1st class coder to start doing pretty complicated stuff very useful in the BH area with it on the desktop side and there's plenty of code around since it's a native windows language. You can design interfaces in hta, having a solid way to reuse your html knowledge should you choose to.
Python: on the linux side if you want to venture into that. Faster and more handy than perl. Many bindings available to build rapid GUI applications too. Most google private internal tools are made with it and I know it for a fact. Nuff said.
C#: When you have a good grasp on coding you can't go wrong with it. I'm not a fan myself (big ansi c and c++ coder since the bbs era), but this is irrelevant, the language is very capable, extremely well designed and the support excellent. With mono (if you avoid pInvokes) you'll be able to run your apps on several different platforms basically the same as java.
SQL notions: some knowledge is good to have to understand key concepts about how data is handled on the web side. Again w3schools will do.
The DONT's
java: what for? A marketer should stay away from it like the plague if he's not a consummate coder already. Totally irrelevant in this area, bloated, SLOW, needlessly complicated for BH stuff (go tell uncle Bob the latest tests demonstrate the execution of that specific math algo is faster than C++..)

Good for making server side apps, good with a tomcat server, unlikely to have any cozy use in BH.
perl: not that useful unless you do security research or heavily into some specific tasks you'll benefit from. Worked with OOP perl among the many jobs I did in IT and honestly there's really no use for it, until you are Cowboy Neal. Nerdy talk, look it up.
haskell, erlang: anything ppl fill their mouths with as "a revolutionary way to code", "a new way to design your apps", make yourself a HUGE favor, write it off. At least for now, someone who starts coding should never ever mess with them unless he has a good grasp on 1. procedural 2. oop programming. The advantages of running are made clear only to those who can stand and walk already. The rest is a lot of psychobabble / guru talk.
It's not a comprehensive list, but should get you started with realistic expectations.