Hello. I am in a similar position as you, just thought will share my experience with you what I have done, what i have learnt so far.
I have started with simple tutorials on various sites, honestly there is hundreds of them, some good, some better. At the beginning, while basically I was copying tutorials written code, I was reading descriptions of tabs, what they mean, what they do. Slowly moved forward, to slightly more complex code tutorials. Once I learnt basics of html4 and css2.1, I started follow tutorials from PSD to code. I assume you should now basic quite well - you done couple of courses. These helped me a lot to understand layout, margin, padding, backgrounds etc. The only problem with most of them, that they are quite out of date... Once I realized that, I started to learn HTML5 and CSS3, and tried to do same PSD's but in a new way, employing css3 mainly. I think it helps to start think as a front-end developer, trying to figure out how to code that PSD layout, what to use, how to use..