I agree with the above posters. If you're going to be doing much with PHP in the future, you're really going to want to get a handle on regular expressions. they can be very complex, but if you start simple, and take it slow, you'll be a master in no time, and you might understand the examples under preg_replace(). I think they are way confusing, since I'm still a beginner with regex, as well.
One of the benefites of learning regex is that they help you to keep your applications secure. You can make sure that people can't enter numbers in your name input, or some malicous code where you were just wanting feedback.
Bad things can happen when people put stuff in input boxes that you never intended. You can verify anything with regex. Its awesome.
Look up multiple tutorials, and read through them all the way. there are tons of them on the web. Good luck.