Amazingly, the software you get with your camera for free will do most of the photo editing we as technicians will ever need to do. Nikon and Canon for example have their algorithms for their own cameras worked out that they actually render photos much better than even Photoshop. Adobe isn't allowed that kind of proprietary information from either company. Of course if you wish to composite or retouch using plug-ins like the NIK suite or onOne, you will have to jump on up to Lightroom or Photoshop.
But just getting your feet wet - and you won't go wrong with what came in the box for free.