This pose is much harder than it looks if done correctly.
Sit with your legs out straight and you feet flexed (toes to sky) contract the quads (front top of leg) so that the knee caps lift.
Roll your shoulders back opening out the front of your chest.
Lift the lower ribs and keep the back straight.
Hands will rest on the floor arms stay in line with the shoulders.
Make sure the neck is straight and the chin is parallel with the floor and gaze towards the toes relaxing the face.