To clean off the front lens element, first start off with using a dust blower to get off any dust that may be on it. Then take a microfiber cloth and lightly dampen it with a lens cleaner (do not use glass cleaner or any other chemical as it could potentially ruin the lens coating). Wipe the front lens element with the damp microfiber cloth using a spiral motion.[br]
As far as water spots on internal lens elements, that's not quite so easy to clean. It would require completely disassembling the lens to be able to get to each internal lens element and cleaning them. If the water spots don't affect the image quality very much, I'd recommend just using the camera as-is. Otherwise you could potentially send the camera into a repair shop to get cleaned, but depending on the price it might just not be worth the money for that camera.