There are few things more irritating in photography than taking some great photos and then getting back to the computer and discovering there are dust spots all over them. Dust spots come from dust (shocking that!) getting into the cameas sensor, usually when you’re changing lenses. So to get rid of the dust spots you need to clean the sensor. There are two choices here, one is to pay someone to do it for you the other is to do it yourself.
If you want to take the do it yourself option there are plenty of guides out there on the World Wide Web but it’s worth checking out this guide at Cleaning Digital Cameras (catchy title, I know). It’s the most detailed I’ve come across and if you have the time and patience to read it and follow the instructions then it can save you time without your camera and a bit of hard-earned cash. Plus, it’s good to learn how to care for your equipment!