This is wide question. And you didn't give any information about your skill level.
If you are totally a beginner, I will recommend you to start by learning rules of poker of course. Then learn some basic strategy, pokerstar school or cardschat poker course. Then I can recommend signing up Advanced Poker Training -site, there you can practise and use it as a warm-up tool.
Then, you can learn poker just by playing as much as possible. Later you can start buy some specific poker courses, like hand reading, reading opponents tendencies etc.
Feel free to send me PM if you want to know more about learning poker, I will be happy to give you some tips. I have played poker for 3 years actively, and I have a lot of experience.