Take the back off and the battery out, get a supply of silica gel or I believe rice and put the phone in a container with some (To suck out moisture) and then after a few days maybe repeat process.
Then try turning it on or possibly charging it.
Having it on charge whilst still damp isn't a good idea as any electric will jump from the charging circuitry to other parts of the phone that maybe don't like so much electricity.
But you could be looking at a new phone all the same.