Although I do not guarantee that you will learn enough to make a commercial website , I can confidently tell you, from my own experience, that you can learn a lot in 6 months. Here are a few tips.
1-Start from the Basics.
Do not in any case think that you can skip the basics, even if they do look a bit easy. This is one of the greatest mistakes I did when learning C++, I skipped the basics. Before trying to use any language, especially advanced ones, you should have a firm concept of the basics. Try buying a good book on the language you are trying to learn for the website.
2-Learn the Easy Stuff First
It is not necessary to start directly from the main stream languages of the web (C# , PHP etc.). Try learning some easy language first. Something educational to make you familiar with the key concepts of Programming. I suggest you learn a scripting language with a nice clean syntax like Python. Or you can learn one of those educational languages like Pascal, though it is a bit obsolete.
3-Try Making Some Simple Programs/Web Pages First
Before starting to make an advanced website containing client-side and server-side code. You should try making something simple for practice and to make you more familiar with the concepts and features of the language you are learning and how to apply those features to suit your needs.
4-Think Like A Programmer
Sometimes the biggest problem and challenge for beginners is how to "think like a programmer". You must understand that knowing all the features and the odds and ends of a language does not make you an expert developer, or even an intermediate hacker :) . You must not only know how to solve a problem but must also know what the best way to solve a problem is.
5-Learn from Other People's Code
Try reading other people's code. The best way to do this is to make a program and then see the source code of a similar program made by an expert. Aside from increasing your programming knowledge it will also make the mistakes and design - flaws of your own code clear. The expert's code may not only be more efficient, but may also be shorter than yours which may teach you how to do more in less code. Increasing your productivity and making your code better.
6-Never Think You Have Learned It All
You must never , never ever, give way to the illusion that you have learned every thing there is to know. Always keep improving yourself and thinking how you can solve a specific problem better.
Resources: There are a lot of resources available on the internet including online books, wikipedia, planet source code etc. But the best resource in my opinion is something that looks for resources i.e search engines like google. You may also buy books but please avoid the ones which have titles similar to "Learn X Language in N Days".
I know with other's help, my learning experience will be both more productive and enjoyable
To contact with experienced developers and learn from them , the best thing you can do right now is to join an open-source project. You needn't contribute to it much, it isn't even necessary to be good enough to be listed in the "Main Contributors" List; just try to understand how and why all the other people coded the way they did. This will easily help you accomplish points 4 and 5.
1: Simple Advice For Learning A Programming Language