First assume a quadruped position, then straighten your legs and raise your hips, to a pike position. To start your shoulders should be elevated, arms straight, and head neutral.
Begin the movement by bending the elbows, and lowering your head towards the floor. Swoop through, hips moving downward, and shoulders and chest come in front of the hands as you drive through and lock the triceps. Hips stay elevated, glutes engaged, eyes forward.
Now reverse the movement, bending the elevating, head lowering close to the floor and hips driving back up as you return to the start. Repeat for repeitions