First of all, use MySQL - the support in PHP is almost identical, but MySQL is used by more people, therefore getting help is easier. If you have a computer at home, install Apache, PHP and MySQL on it - it's very handy for testing and playing with things.
Start off with the tutorials and articles on
www.phpbuilder.com and
www.devshed.com . Play around with the simple stuff, and if you run into trouble, ask on
www.phpbuilder.com/support/ . Keep copies of the PHP and MySQL manuals locally for reference, and READ them - they're pretty good manuals on the whole.
If you're into book-learnin' (doesn't suit everyone), you'd do well to read Professional PHP Programming - it comes highly recommended, and the author (Jesus M. Castagnetto) is a regular on the phpbuilder.com support forums, and a nice bloke to boot. For SQL information, The Practical Sql Handbook seems to be the most recommended.
Finally, if in doubt, ask. The phpbuilder.com forums are a real mish-mash - you get all sorts of questions - installation, coding, MySQL, image creation and anything else related to PHP. The people there are very helpful, but be warned -
don't ask without trying to figure it out yourself first, by checking the manual and searching the forums and mailing lists.
It's a busy forum and we don't have time to answer questions that have been answered before. If you
do ask, prepare yourself for a lot of very short replies with RTFM's sprinkled liberally throughout...
Most of all though, have fun!
adam