Hi! I know how bad it can be to have water damage on a MacBook. I am no expert, but I can give you some basic guidelines as to checking and repairing water damage. Assuming you have a pent alone screwdriver, you'll want to take off the bottom case of the MacBook. I recommend iFixit's guide for this. I would then use the visual test to check for water damage. Finding the damage is one thing, but repairing it is another. To get a better idea of what's wrong, was your Mac powered on when water was spilled on it?
MacBook Pro 13" Retina Display Mid 2014 Lower Case Replacement