You can take the bottom off, and check for moisture that's still inside.
It may still be wet inside. Clean off as much as you can with isopropyl alcohol.
If there's no visible moisture inside, then you could try connecting an external display. If an external display shows a good picture, then I suspect the internal display cable, or the display connector on the logic board. Again, alcohol around that connector. Reseat that connector, and then try the display again.
no visible moisture? good grief. that's hardly a good thing to rely on.
it is not easy for a non-techie to take an MBA apart. pouring water on an MBA is a good way to kill it.
lots of threads in the forum for trying to recover. Usually air + active MBA = dead MBA.
The longer it is wet inside, the more likely you will have serious (expensive) damage.
My opinion is that you should open it up the same day as the spill, even sooner, if possible.
If you don't have the correct tool, then that makes it more important to find a shop to take it for an inspection.
You probably won't find that tool in any usual hardware shop, unless they also sell some other special electronics repair tools. It's available easily on line, but you need to open that up sooner.
Before you even think about opening the laptop, go to ifixit.com and look at the disassembly instructions for that model. Either you'll come away with an "I can do that" attitude, or you'll run to the nearest repair shop.
Liquid can do all sorts of damage, and much of it is not obvious. As there's electricity involved, electrochemical corrosion starts quickly and, even after the thing seems to be fully-dried, can continue. Slow decay. New problems can pop up weeks and months later.
The sooner you can get this attended to, the better your chances of success. If you can't get the right screwdriver immediately, take it to a shop that can do the job, ASAP.