Jonas,
What do you want to do? That is the real question. I got into coding when I was 11. At the time what I wanted to do was just get some attention, be a part of the big internet. So I learned HTML and that was sufficient.
As I progressed I wanted more. I wanted a site that looked good, so I improved my graphic design. I wanted more flexible pages, so I picked up CSS.
When blogging came about, I was intrigued so I learned PHP. Not
all of PHP. Just what I needed, function by function. This continued and while you learn something new you further develop your existing skills.
When you have a firm goal or project in mind, it becomes clear what you will need to accomplish that task (and if it isn't clear, you can always ask here
).
Of course, it would be best to know every language and every discipline. But it's more realistic to have a project in mind and to learn what is necessary to accomplish it.
So, what do you want?