Your camera is capable of ISO adjustments from 100 to 1600. Photos taken at ISO 100 require the longest exposures and will have the best quality color and least amount of graininess. This setting should be used as often as possible and is ideal for well lit subjects. Conversely, ISO 1600 is for low light situations. Photos taken with the camera set to this value will have muddied colors and much more graininess in them. This is often preferred to having no photo at all.
The down side to this camera - like most point & shoot ("P&S") types, is the fact the the light sensor that actually captures the image from the lens, is quite small. Small sensors have difficulty rendering acceptable photos when taken at high ISO settings. It is not unusual for P&S cameras to perform unacceptably at ISO 400 and up. Reviews I have seen on your camera back this up. Basically, ISO 100 and 200 are the only values that provide acceptable photos. You should experiment with the entire range of ISO under different lighting conditions to see which situations and ISOs are acceptable to you.
Your camera makes use of icons to access menus and they do not show up well on FixYa, so I will need direct you to an online manual that you can view or download. It can be found here
Chapter 3 (begins on Page 16) talks about camera menu settings. Your should review this chapter, and pay particular attention to "ISO" on page 20. You will learn how to select ISO 100, 200, 400, 800 & 1600 on the camera.
I hope this helps & good luck!