A tablet is hard to get used too. And the thing about a tablet is that it's the same as any other drawing/painting tool, you just avoid the mess and can do it anywhere (well, anywhere you have a computer). So technically, you have to already have the ability to paint/have practiced a lot with it. Having it doesn't mean you'll be able to magically be able to do what every other artist does.
And I've realized that it is really hard to "teach" someone how to use a tablet/paint good... because really, it's just lots of practice. So, I would advise looking up a few tutorials on how you want to paint. For example, if you like the way Rescreatu artists paint you should look up "cell shading" since that is the style they use.
Cell Shading tutorial: http://www.jamihn.com/artschool/tut_cell.php