This is what is on the main site under surfing lessons:
Place both hands on the rails out in front of you and push downwards, sinking the nose of your board under the water.
Keep your arms straight and lean forward to help get more of the board under the water.
Just before the wave breaks over you most of your board should be submerged - make sure that you take a deep breath.
As the wave starts to go over you you should lay out flat creating as little resistance as possible your knee or back foot (for extra deep dives) should be putting pressure on the back of the surfboard, leveling it out under the water.
As the wave passes over, angle your board back up to the surface. If you have duck dived correctly you should be in a position to immediately start paddling again. The quicker that you can resume paddling out, the quicker that you will get out back and the less energy you will be expending.
Extra tip:
Pratice timing the most as this can make or break your duckdiving success. (that was my main problem anyway).
Good luck!!
