Tree :: Vrksasana
This is a balancing pose. Focus first on placing your feet against your leg. You can hold it there with your leg if you need to, while you build up the strength needed to keep it up on its own. Press your foot into the side of your leg and at the same time, press the standing leg in towards the foot. This pressure will help support the foot and allow it to stay high up on your leg.
Find balance by shifting your body weight around slightly until you find the place where your center of gravity (just below your navel) is directly above you standing foot. You will know when you've found this sweet spot because the effort required to stand balanced will disappear. Maintaining balance requires an internal focus. You may notice that if your mind wanders or is busy chattering, you will struggle. Once you've quieted and focused your mind, your balance will come more naturally.
While you're finding your balance, and beginning in the pose, place your hands, palms together, in front of your chest. Only once you've stabilized and are feeling comfortable in the stance, should you flex your shoulders overhead and straighten your elbows.
This pose is excellent for developing a sense of balance. It helps to strengthen your ability to focus your mind, and tones the muscles of the legs.