How to heal muscle tears in the upper back ?

Rest : Back muscles take time to heal. Acutely you need to rest, use ice, and an anti-imflammatory drug like Ibuprofen or aleve (naproxen). Once the acute pain subsides heat can be used and gentle stretching. You may also benefit from sessions with a therapist.

Posture & strengthen: Sounds like you are suffering from myofascial pain. Freshly strained muscle needs time and rest, and take caution not to overstretch the affected area-- this means pay very close attention to your posture (esp sitting, driving, sleeping). Then begin gentle strengthening of the scapular retractor muscles. Use good biomechanics with any lifting, which could reinjure you. Maintain good posture.

Posture & strengthen: Sounds like you are suffering from myofascial pain. Freshly strained muscle needs time and rest, and take caution not to overstretch the affected area-- this means pay very close attention to your posture (esp sitting, driving, sleeping). Then begin gentle strengthening of the scapular retractor muscles. Use good biomechanics with any lifting, which could reinjure you. Maintain good posture.

Rest, time: "Strains" to paraspinal muscles primarily need rest and time. If progress is slow, physical therapy can sometimes be helpful.