For the benefit of the generation that have only ever used Instagram, there are two file formats recorded by the 1520...
Raw with a file extension of DNG and regular file format, with an extension of JPG.
The JPG format files (also called JPEG for short) are the ones that are usually the 5MP images.
Rather than write a long essay here about the differences between the two types of file formats which I'll let you look up on Google or Bing or whatever, for upload to most web sites, 5MP is all you need as no computer display actually shows more than that and sites like Facebook always seem to downsize images to less than about two megapixels anyway, and will not display raw files anyway so there is little point in anything else for you to bother with, unless you are going to produce a 16x20" (or larger) print of everything.
By the way, always shoot in good light. The grainy (actually it's 'digital noise') and the less than great colors are usual for when there is not enough light and you don't use flash. Set your camera to the default or auto settings if you have any doubt, as messing about with these settings if you don't know what you are doing is an easy way to mess the results up.