Re: Help with Powershot A520
if you're using no flash indoors with that camera, all your images are going to be grainy. it just doesn't have a big enough aperture to be able to capture images at low ISOs, so it will go up to high ISOs and get that dreaded noise. You can keep your ISO low, but then you will be dealing with lower shutter speeds.
1) changing the shutter speed will allow you to keep the shutter open for longer, therefore changing the ability to freeze action. The shorter the amount of time the shutter is open, the more action will be frozen. the shorter it is open though, the less light can get in, which will result in dark photos.
2) changing the aperture will affect the depth of field, and again the amount of light coming in. a bigger f/ number (smaller aperture) will let in less light and will cause the image to be dark.
3) ISO speed is how sensitive the sensor is to the light that is coming through. say you are dealing with available light inside, you want your sensor to be a lot more sensitive to the light than if shooting in the sun, because that way it can take the image as quickly as possible. but the higher the ISO, especially on a point and shoot, the more noise creeps in.
4) metering mode just refers to how the camera is selecting how light/dark the photo should be. whether it is taking its reading from a point, the weighted center, or the entire scene.
Re: Help with Powershot A520
Welcome ugess.
All your questions can be answered in the How Tos.
The link 'Photography Exposure Primer' should answer all your questions. If not holler back here.
Edit: Oops, Brent beat me to it.
Re: Help with Powershot A520
Hi, uguess.
Brent covered the exposure issues nicely, but I'll add one thing that I find makes quite a difference in the circumstance that you describe. With the unnatural lighting that is normally available indoors there is often a rosey/yellowy hue to the photos that also serves to darken them. You can correct the colour by switching from AWB (auto white balance) to Custom. Check your manual for how to do that, but you probably select Custom, point the camera at something white, and press the set button. This tells the camera that this is the new white and it adjusts colour accordingly.