One of the best resources to learn HTML/CSS step by step is using the lynda .com video tutorial series.
If you are more a visual learning type this site will change your life!

Ya W3schools is the best source to learn HTML, DHTML, PHP etc.. They have explained each and every thing with examples so that anyone can learn easily..

Start with trying out, make a lot of mistakes, and ask a lot of questions. Try to build something you will enjoy first.

HTML is one of the easy language to try with. You can learn it in couple of days, and can customize a simple HTML website. On the other hand next step after HTML is CSS which can take a little time for you to become expert.