A great pose to start with when you start one of your yoga sequences is Mountain Pose. Also called Tadasana. This pose is done by standing straight with you are slightly from the side of your body and your fingers stretched wide. Then you would bring your hands directly above your head with arms lined up with your ears.
This pose can you used to strengthen your knees, thighs, and ankles. Mountain pose is one of many standing pose. Standing poses can be use to start a yoga sequence like sun salutation for example.
Moving with the breath, in the sun salutation sequence you start mountain pose with your hands slightly away from your body. Then you bring your arms above your head aligned with our ears. After which you add a slight back bend (making sure not to do more than you body allows). Then you bring your arms down so that your body transitions into a standing forward fold. You come up half way placing your hands on your shins, making sure to have a flat back. Go back down to standing forward fold placing your hands on the mat/floor. Then move one foot behind you to transition into low lunge, then move the other foot back. Now you will be in the plank position. You can slowly lower yourself down to the mat/floor to transition into cobra or upward dog. You then transition into downward dog. From this pose you can either move you legs one by one back to the front of the mat/floor to get into standing forward fold. Or if you are a little more experienced you can jump to the front with both feet. Once at the front you bring your hands to your shin making sure to have a flat back, then back down to the floor or transition into chair pose. After which you stand back up transitioning into mountain pose with your arms aligned with your ears and hands high. Then lastly moving your arms back down by your side slightly away from your body. You have just finished your first yoga sequence, Sun Salutation.