Go for it.
I personally think some DH racing is essential to being a complete mountainbiker.
As mentioned above go for a local series, maybe on a low elevation hill to start with, just to get used to the way a DH race works. In addtion to above have a look at the southwest series run by kustombikes.com.
I would look for a race with a hardtail cat(these days most have one), as this will allow you to be competative and also understand how fast you are (or as I found out when I first started how fast you arn't).
As in all scenes there are some idiots so take everything you hear in the uplift queue/push with a pinch of salt. Having said that most of my best friends I have met in a quarry truck going up a hill in wales so it is usually very friendly and there WILL be lots of people in the same boat as you. There are lots of riders who will humour strange questions and most people are supportive of new riders so don't be afraid to ask silly questions to other riders.
Take the time to know what marshals flags mean, and learn a little uplift and track etiquette. Most of this is common sense but don't stop on blind areas of the track, don't stand on the track during practice and try to yield to faster riders during practice in sensible way. during teh race on a small hill you shouldn't have to worry about other riders during your race run.
As far as teh racing goes The hardest thing with Racing I found was reading a DH course properley, so make sure you walk the course and take the time between runs etc to watch some sections so you can see how it should be done.
I would also say don't get fixated by any particularly scary lines that look terriying there is always another way round or over (ok its slower) and sometimes worrying about if your going to do a particular feature can dominate your day. To start with focus on teh things you are fast on and do enjoy. There will be plenty!
Have Fun!