Standing yoga poses can often be quite challenging, especially for beginners who are not very flexible. A good way to start is to use a set of yoga blocks under your hands to help you achieve correct alignment and to hold the poses longer.
Stand upright with your feet together. On an exhalation, bend forward at your hips and place each hand on a yoga block. Make sure each block is directly below the shoulder. Shift your body weight slightly forward so you are balancing over the middle of your feet. This way, your hips can line up directly above your ankles. Pause for a moment, lengthening your chest to maintain a straight, long spine.