If you are looking for a free option Picasa is probably your best bet. You can match it up with Gimp to do some more advanced editing. The preferred solution by many is Adobe Lightroom, which you can find on sale for around $130USD right now I believe.

Depending on the camera that you bought, you likely received a disc of software with it that may even include some pretty good digital asset management software of its own.

Resources

This question that has many answers might help you, although it does cover paid as well as free options: What software is focused on reviewing and organizing images?

A great group of articles can be found at this link: http://www.neocamera.com/article.php?id=dam-software It explains in more detail about how using digital asset management software can benefit the photographer, as well as going into detail about the paid options available.

A blog post at this very site may help you out as well, it specifically outlines the options available in Adobe Lightroom, but the same basic feature set exists in any digital asset management software such as Picasa or Apple Aperture. Here is the blog post: http://photo.blogoverflow.com/2011/10/lightroom-fundamentals/