Hi David
First thing is remove the battery!
Open the phone up using a credit card around the edge. If it fell into anything except clean non-salty water rinse it off with tap water prior to drying. Give it a fairly vigourous shake (though don't let it fly out of your hand!) to remove as much water as you can.
Leave it somewhere warm (not hot) and safe to dry. I'd recommend a couple of weeks.
Reassemble and hopefully all will be well.
Don't give up hope - I dropped a running Dell laptop into a bath full or water. I followed the above, and all was well. 2 years on and it is still running fine.
Good luck!
Ray