I recommend learn the bare bone basics.. they are HTML and CSS, after you are comfortable with
HTML &
CSS, you might want to learn a little bit of scripting with JavaScript (or perhaps not, up to you).. Any good web designer is good with the basics! (HTML & CSS) Just google "HTML Tutorial" and "CSS tutorial" etc. or head on over to wc3schools
As for graphics, and layouts, etc. You should learn how to use graphics programs like Photoshop, The GIMP (free), Paint.Net (free), etc.
Once you understand a little HTML/CSS, you can download free website templates (google) and go through the code and you will pick up certain habbits for site designs..
If you want to make a job (or career) out of it. I definitely recommend you get your own website and put up some of your designs, what you know, etc.
Start of small, adding a few designs, improve, add some more designs, advertise, etc.
Hope that helps
Shaun.