You can learn the yoga asanas online in this series. You can find their descriptions here, and the videos help you learn how to do them.
This exercise improves your posture and stretches your legs.
Stand straight, and then get into a hip-wide straddle. Stretch your body, and lean forward gently, vertebra by vertebra. Grab your big toe. If you cannot reach it, you can use a strap, or just grab your shins. If you reach the big toe, stretch forward with your backbone, and push the sitbones upwards. Tighten your thigh muscles to protect the knee joints. Stretch with your backbone intensively, and push the sitbones upwards. the spine and legs are stretching.
Slowly rise up, stretch your body, and step back into straight standing position.
