Congratulations! You've reached the end of this tutorial.
You should now be able to create some very functional, dynamic websites using PHP as a server side language. There is still much more to PHP though, so I encourage you to keep learning.
Now that you've seen what is involved in PHP programming, you might like to compare PHP with another server side language. Try the ColdFusion Tutorial and you'll see that many concepts are the same between different languages.
You may find yourself in the situation where you need to create a database driven website. In that case, you'll need to know about databases. Also, to query your databases, you need to know SQL.
And, I did say at the beginning of this tutorial that you should have experience with HTML before continuing with the tutorial. If you chose to ignore me, and you still understood this tutorial - well done! In any case, now would be a great time to learn HTML!.