First off, unplug your PC. You don't want any shortages. Also, make sure the water didn't go on any other hardware.
Make sure to remove your graphics card, and completely dry it. I recommend using a hair dryer (don't make it too hot) and a microfiber cloth. Try to avoid using those paper towels!
When it's all dry, put it back into your system, and it should be fine. As long as you did not run it while it was wet! Hope I helped.