Tap the on-screen Arrows to move. Avoid the guards and get to the vent to proceed to the next level. Hold down the screen to speed up time. When guards aren't facing you, you can slide into them and shadow their movements automatically. While shadowing them, press a movement key to slide in the opposite direction of the guard.  

In later levels, you'll need to collect data sources in the correct order to unlock the exit. The order is indicated at the top of the screen. Also, you must be moving up or down to collect vertical slices, and left or right to collect horizontal ones.