To start you just need to click
signup, provide username, password and email and click the button. You're in!
Now click
play on the main menu: some options will appear. You can begin with an easy approach:
hiragana or go straight for gold:
kanji!
When you signup your level is set to 1 and you got 0 EXP points. Each character you recognize correctly will be worth you some experience points. Those EXP points increase your position in the overall ranking, eventually they allow you to level-up and also feed the dynamic-kanji-engine that shows you different kanjis to recognize depending upon your skill.