How do I use my power power-ups and boosters?

Where are you clicking on them? To use Power Ups, you need to select them from the level screen before you hit play (on the left side). You'll only see three of the six options. Clicking on one or more of the three should add a green checkmark. The boosters are used in-game (except for free round, which is automatically applied to the next round you play). Wild cards are on the bottom right of the screen, click to add it as the current card. Undo appears to the right of your current active card (appears after the first move). +5 appears if you run out of cards before finishing the level.