This is what i have seen from some dock diving trainers: finding high value motivator (one vizsla needed a frozen bird...) and keep calling the dog with it, holding it up, splashing, making it look lots of fun. Have another dog they like jumping in and see if they will follow or just make them watch to want them to jump. Praise every little step as if your dog had just won the Olympics and keep it fun fun fun. If there is a lower dock they can jump in from first, the better.
Bende and Miksa have been puppy jumpers as they had access to the pool, so for them it was easy to transfer it to dock diving pool. Nevertheless, every time they are on the dock, we are having lots of games. With Miksa no discipline yet, like staying in place or so as he is still very immature, so don`t want to kill the joy an make him not want to jump anymore. Bende can already handle more pressure, but gets a reward of tug o war on the dock after every jump. That is what he likes doing post jumps.