Click the long purple button at the bottom of the intro page to log in. Once you are logged in, you can access the game by clicking the pink button on the bottom right side of the screen.

Each level has a villain to beat, and each villain that appears is in chronological order of the Sailor Moon Story Line. The higher the Level the harder it gets.

When you point the arrow, try to get as many of the orbs of the same color you selected. The more orbs successfully hit the better chance of defeating the level. Also note that you must play quickly! Underneath the villain, you will see a blue line: that’s the villains health. The more you hit them the blue will diminsh. This helps in knowing how much more is needed to defeat them. The timer is in the top left. When you are almost out of time, it will begin to flash red.
If you beat the villain with time left to spare, tuxedo Kamen will replace the villain and essentially you get this to make bonus points. The game keeps record of your high scores, try to beat them! You’ll get more crystals too!

During game play, points and crystals will build up, and also the power-up of whichever Senshi you are playing. If you score enough points quickly the powerup can be used and will light up with a sound effect on the bottom left. For Sailor Moon her attack is her Boomerang attack.

As you progress in the game you and your Senshi will level up as well. I think the highest is level 5 for each senshi.

In order to get more senshi click the makeup! Button on the main map page of the game. There you will see a page with Sailor Box on it.
If you have enough crystals the box will give you a senshi to play. I don’t know for sure if it is random or chronological order. My first box was Sailor Moon.

Another way to build up crystals is by receiving Silver Crystals/Ginzuishou in the daily gift box on the upper right part of the map screen. You can exchange them for more crystals in the Sailor Box. You also recieve crystals in the daily gift box after you emptied your hearts.

This is the gist of the game, if I learn anything new I’ll share it here.
Hope that helps!