As quoted on http://www.digital-photo-secrets.com/tips/blurry.html:
Stop Blurry Images
While it's impossible to fix an already blurry image, there are a number of ways to ensure future images are ultra sharp - each with it's benefits and disadvantages.
1. Turn on the flash! Modern cameras warn you if they think a flash should be used - usually by flashing a hand symbol (which basically says you'll get a blurry image if you take the shot while holding the camera in your hand). A flash will provide enough light for the camera to use a quick shutter speed and stop the blurriness. The disadvantage of using a flash is the flash light 'dies away' quickly, so only the subjects close to the camera are fully lit. The background will be very dark.
2. Use a tripod. This will steady the camera while the shutter is open. When shooting people, you also need to ask them to be still while the shutter is open. You also need to be aware that your finger depressing the shutter button will shake the camera, so you should use either the timer, or a remote trigger, so the camera is still when the shot is taken. This method works well when you want to take shots of inanimate objects, but not so well when taking shots of people, such as in this photo.
3. Use "Shutter Priority Mode". Some of the more expensive cameras have a shutter priority mode that you can use to override the camera's default shutter settings. Using this mode, increase the shutter speed as far as you can go. The camera will compensate by opening the aperture more (to let in more light) and also increasing the ISO value (so the camera needs less overall light to get an acceptable image). If you use this method, your images may turn out to be too dark, so either take a few shots at different shutter speeds, or increase the EV level to brighten the image. This method also tends to increase the 'noise' in the image.
I also recommend practicing. Practice taking some more indoors shots using each of the tips above. Make a note of which settings you used for which shots, and then check the images on your computer. Note which ones turned out best and use those settings next time you need to take shots in that situation.