I like digital art and paintings. I want to create my own.
Which software/tools do I need to accomplish this?
Three popular digital art applications used by both amateurs and professionals alike, in order of price (low to high):
And of course Photoshop you clearly already know about. As others have said, get a good graphics tablet early and get used to it early, and a Wacom Bamboo tablet is pretty much perfect for beginners in price and quality.
Also, since practicing often is key, consider mobile devices:
MyPaint is a nice open-source digital painting application. The results look fairly realistic, but it doesn't have some of the nice media and brushes that paid applications have. But it sounds like you want to get your feet wet, and for that, this would be a great project. I've produced works-for-hire with it, and the clients loved the results.
One tip: get a Wacom tablet, of course. Bamboo tablets only cost $80 CAD nowadays. It's pretty much essential for painting, because of the pressure-sensitive pen.
Digital art can be created with hundreds of different programs. Many tutorials for photoshop etc can be found with a simple google search.
One such tutorial site is www.psd.tutsplus.net
I would go for Free Software tools like GIMP or Krita. Krita is more specific to digital painting, and is somewhat simpler.
However, if you can put your time in it, GIMP will give you more power in the long run, but there is a lot more to learn, too.
Free alternatives to Adobe products
For professional work, I'd strongly suggest you get a Wacom. Although the portability of a tablet (iPad/Touch) may come useful for sketches, they do not have the level of control or refresh rate. With a Wacom, in addition to better pressure control, you also have brush angle (tilt) and can use it within professional software that doesn't run on a portable tablet.
Software wise, I'd recommend Photoshop or Corel Draw. Corel Draw may be better (although I've barely used it myself several years ago). Looking at the Corel website, they have a program called Painter X3, which looks like a stripped down digital painter focused version.
I remember Corel Draw having a lot of digital paintbrushes that mimic real world mediums like charcoal, oil, pastels etc. I believe it also allows you to mix together (affect/blend to the 'wet paint' underneath) as you paint. It also allows you to easily rotate your page/document. This is really handy because it is hard to create long, smooth brush strokes in some directions, so you can rotate the page to your natural hand movements.