To give yourself more latitude when it comes to editing your images, it's worth shooting RAW – that is, setting your camera to save your images as RAW files rather than JPEGs when you take them. A RAW file is essentially a digital negative that contains the raw, unprocessed data from your camera's sensor, from which you can produce multiple interpretations of the image. JPEGs are already processed by the camera and are easily shareable straight from the camera, but give you very little headroom for editing or correction. One practical way to get the best of both worlds is to set your camera to save both RAW and JPEG – that way, you get a picture you can easily share and also a RAW file you can enhance and experiment with later. Be aware, though, that you will need more room on your memory card for your camera to save both versions of every shot.
In order to create a photo from a RAW file, you need to process it. You can do this in-camera, and even make some adjustments along the way, tweaking the brightness, correcting lens aberrations, applying preset effects such as Vivid or Soft, and more. It makes sense, however, to do the processing on the (much larger) screen of your computer using specialist RAW editing software, such as Canon's free Digital Photo Professional (DPP) or Adobe® Lightroom®. It's easy to do, and gives you the opportunity to apply a different Picture Style, white balance, noise reduction setting and much more. Any edits you make to the RAW file (whether in-camera or on your computer) are non-destructive, which means the original file is unaffected and any adjustments can be undone, tweaked or removed at any time, even if you close the file and reopen it later.