Have a look at this great RegExp online editor and tester:
It's a fabulous tool though it does take a bit of getting used to it has recently basically taught me RegExp. Just try playing around with different things! The side bar contains all the RegExp symbols, escaped characters, expressions etc and examples that you need to produce really complex RegExp. It even highlights matches for you and will let you do find and replace tests to. It also 'tests as you type' :) Final thing is that it will split your expression up for you to show the different groups and any errors.
Hope this helps,