Good morning Mattie. I'm so sorry that this happened to you. Please follow these steps for your best chance at reviving your phone.
Turn off Your Phone! Don't just turn off the screen. Power it down completely. Unplug it if it's in the charger (and do not plug it back in.) Hold down the power button until it is off, and if possible, open the case and remove the battery. Do this immediately.
Generally, phones don't die just because of water. They die because the water causes a short in the wiring. In order for that to happen, you need to have power. If you can power down the phone and dry it out within 48 hours of water exposure, chances are good that your phone will live to see another day.
If you have a case on your phone, remove it at this time. You want to have as much of your phone exposed to air as possible.
The worst-case scenario is if you have a phone that isn't designed for easy battery replacements( like an iphone) that won't turn off when you try to power it down. I had that happen once and opened the case with specialized tools to remove the battery. Without those tools, the best option would be to lay the phone flat and hope the battery drains before anything shorts.
If you dropped it in the ocean, wash it. Salt water will corrode the interior. Same if you dropped it in soup or other materials with particles. Or a dirty toilet bowl. Yes, wash it off in a stream of clean water. Do not dunk it in a bowl or sink of water. If there's water inside your phone, you don't want to make it worse by letting it run in new places.
Most people will tell you to put your phone in a bag of rice. However, Rice is not a drying agent. Do not use rice. Instead, use actual drying agents, such as Damp Rid (available in grocery stores) or silica gel (the "do not eat" packets you find in vitamin bottles).
Gently pat your phone down with a towel, and then place it on some paper towels. Place the phone somewhere where it won't' be disturbed. If possible, place the phone and paper towels in a container with Damp Rid or silica gel packets. (Not loose powder - you don't want particles in your phone) You probably have time to run to the grocery store to buy some if you don't have any on hand.
Now you wait. Give your phone at least 48 hours to dry. Longer if you can. You may want to balance your phone upright and tilt it, so the USB port aims down after about 24 hours to make sure any remaining moisture drains downward and out of your phone. Avoid jostling or shaking.