Learn photo editing and post-processing using tutorials that are independent of software type. When done correctly, this can help you to get that "keeper" image looking just right.
Although these tutorials aim to be independent of your editing software, recommended programs include Adobe Photoshop or Lightroom, GIMP, Aperture, or whichever program came with your digital camera. One should ideally performed all editing using RAW image files, but most of these tutorials can also be used with JPEG or TIFF images.