Plank: Start similar to pushup position. on knees and elbows, when ready straighten legs while maintaining straight back and hold your self up for as long as you can Ideally 30 seconds to 1 minute but if you can do 10-15 seconds that is ok just find a starting point.
V-up: You will start on your back with arms and legs straightened. Then while maintaining body on the ground and keeping limbs straight, move limbs as close to touching each other as possible and then return to starting position.