Time, practice and perseverance. It will probably take you a few years to "master" anything big.
On the practical side, a few things, that you will eventually achieve if you follow my first recommendation:
First of all you should improve you english skills. The best documentation (sometimes the only available) is in that language. Also you'll be able to better communicate your problems and comprehend the answers given back.
After that, install one of the "easy" distros (like Linux Mint), and start learning away. If you can, set it up in a virtual machine, that way you can take snapshots from time to time, and in case you screw something up you can just go back to a previous state of your OS.
There are lots of resources to learn, you'll find more info right here at LQ, but there's also Wikipedia, the Stack Exchange sites and, well, literally millions of sites and tutorials.
Getting back to what I said at the beginning, the first stages of your learning will be harder. So that is where you might feel a little discouraged from time to time. This is natural and the only way to solve it is going through it. So good luck and don't give up!