Water, and more critically, tea, coffee, juice and several other liquids, are electricity conductors. So if they get onto a chip inside your computer, or even form a bridge between two components that should not be connected, they can cause burnout and the failure of various elements of circuit boards. This is the most obvious type of damage done by water.
Shut it off! Immediately remove the battery, the A/C adapter, and unplug the device after the spill. The biggest danger at first is the device shorting out. The electrolytic activity of combining electricity and liquids will begin as soon as the liquid contacts the powered circuits so removing the power and battery immediately is essential. Turn it upside down immediately to stop the liquid from traveling deeper into the machine. Clean up any part of the spill you can get to. Use paper towels or any absorbent material that is lint-free. Wipe up anything sticky. This may include the screen, the keys on the keyboard, and any buttons. Use a clean, slightly dampened, lint-free cloth. Disconnect and remove any and all external devices.