I don't. I tried to learn Javascript that way and could never remember anything once the tutorial was over. After a while, I just decided to make a big code that did a bunch of stuff. It took a little while, but I made it and got a much better understanding of the language that way than I did doing all kinds of little tutorials.
I also learned another language that way (I've never done C++ but I'm told it's very similar). I tried a bunch of different little things and could never quite remember stuff. After a while I figured I'd just create a combat code for an MMORPG and after a while, I had a working code. After that, I made a code for various spells, then another code for picking up, dropping, equipping, unequipping items.
I always seem to learn a lot better when I jump into something big rather than trying to learn with small tutorial codes.
I do agree with you on one thing, though. Modifying an existing code does help. I learned a lot by doing that, too. The problem with that is I can't find any large php codes to modify. Every time I download a script for something it's always several folders and files of all kinds of stuff and that's WAY too much stuff to dive into.
Thank you both for your responses. psalzmann, I didn't even think about the idea of a database for some reason. I'll mess around with that, too, then try this guestbook thing.
edit: two posts while I was typing this one. Thank you both for the links. I'll explore those now.