You can get all the available PowerUps using the coins you obtain when placing the different words on the game grid.
To get them, go to the Shop that can be found on the lower right corner of your screen. After you enter, you'll see your coin balance on the upper left corner, followed by the corresponding balance of every PowerUp: Top Play, X-Ray Glasses, Word Spotter and Magic Play.
If you scroll down, you'll see the different packs you can get for each one of them, with their corresponding prices, in packs of 1, 3 or 5 PowerUps.
You can now buy PowerUps during the game! To open the Shop, press the PowerUp you want to buy, which can be seen over the board game.
Once you do this, you'll see different options to buy PowerUps, and you'll be able to use them in the game you're playing.