When doing some of the poses that make up basic hatha yoga, you should never feel pain. You must breathe deeply and naturally as you do the asana. As you breathe and move, the poses will come more naturally. You should never strain, but gently increase your ability to complete and hold each pose. If a pose feels difficult or painful, stop immediately and try it as you feel more secure and focused. If you already have any severe back or neck injuries or issues, you should check with a doctor before you try to do any yoga poses or techniques.
There are all different types of themes that yoga instructors use. Some are for the type of students in the class, i.e. gentle yoga. Others are structured around a specific body part or type of pose, like backbends.
Pranayama is the fourth limb of Astanga yoga, and is also called as the "Heart of Yoga." Pranayama teaches us to how to use our lungs to the optimum capacity; as a result of which, the cells in our body are able to get sufficient quantity of oxygen. Though there are about 20 pranayamas; some of the pranayamas which are easy, and can easily be practiced by beginners are as follows Sunhat pranayama, Pranava pranayama, Kapalabhati, Anuloma Viloma pranayama, Bhramari pranayama and Sheetkari pranayama.