I changed my header.......what is Html anyway???

So I watched this tutorial over at freevlog that walked you through changing your header. It looked so simple. I followed it step by step but then realized we were working with different templates. I, knowing nothing about Html except for what I have experienced today, couldn't figure out (at first) how to get my new jpeg header into the spot I wanted it. I guess Ryanne gave me just enough info to make this Html illiterate person somewhat dangerous regarding my blogger template. [By the way: thanks, folks at freevlog, for all those awesome tutorials.They have been super helpful.]
Seeing as I had a bunch of other things I needed to accomplish today. I laid those things aside and began to play with all the Html code "thingys" until I got my picture to stick in a place I could be fairly happy with. I deleted a bunch of other stuff too like the title and description. Well I hope I didn't do any damage. Things look good to me so far. My journey into Html made me wanna learn some of this language. Especially since I am sure I'd like to do some changes to my side bar. Cool, I like to learn. It'll be fun.
I found a site that I haven't really looked at much yet, to tell the truth, that has to do with Html. Maybe I'll check it out later and see if I can learn anything. I think it is called HTML Goodies. If you could suggest any other places where I could learn about this interesting little computer language especially as relating to changing and improving some of the things on this blogger page I'd appreciate it.
Thanks and good night.
anthony