If you've already set up your MySQL server or have one on a web hosting service, just download the official MySQL manual from www.mysql.com and start reading.
It will take you an hour or so to get the hang of it.
Start with some basic tables and queries, then work your way up.
Using this forum helps too....
PHP isn't that different from other scripting languages. You've just got to persevere and it gets easier and easier as you develop quicker techniques to get the job done.
I always go to www.php.net and check out the examples of code when I'm not sure how to use a particular function.
Anyway, that's my 2 cents worth,
Good luck.