HTML/CSS/Javascript isn't too difficult at all.
w3schools is a great resource for beginners, and there
is quite a bit of money involved in actual web design.
Having a good artistic design ability is apparently not as straightforward, unfortunately. There are of course online resources for that, but the greatest resource is a good work ethic. This isn't to say it's too difficult, but it's easy to stray from good design if you don't simultaneously pay attention to both details and the big picture of the layout and user interaction of your website.
You appear to be young (no offense if you aren't), so you have a lot of potential if you begin learning the world of web design now. Hope this helps!
