Personally, I believe most answers are making it complicated more then it has to be. Unless I missed something as I am answering this on my cell, your question is what do you need learn to make a website. Not multiple websites. And you don't say anything about making this you're career.
All you really need are HTML and CSS. A great interactive website might include some JavaScript, or jQuery, but it doesn't have to. Frankly many have created beautiful websites with just HTML, CSS, jQuery. Only other thing you need is somewhere to host your website. You don't need PHP, Python, Ruby, or any other things everybody is telling you.
However, if you are looking to make web design or front-end development your career, then yes, you do need to learn JavaScript, jQuery, and few JavaScript frameworks some here have suggested. Still, there is no need for anything like Python, Ruby, PHP, etc, but they would greatly propel you toward front-end development career.
Unless you are looking to become a back-end developer. In that case, all the programming languages mentions so far and their frameworks will really be your main tools. At that point you are going further away from visual design and more towards programming. Which, in itself is a great career to pursue.
It would have really helped if you added more detail to your question. Right now it's way too broad, and you'll be getting all kinds of answers.