Your hands should be shoulder-width apart and spread your fingers out wide. Press your hands into the floor and gently tuck your toes under and take a deep inhale, then keeping your hands pressed into the mat exhale deeply, lifting your knees off the floor and straightening your legs as much as you can. While in this position make sure heels are pressed into the floor. This should help relieve tension in the calf.
While heels are pressed into floor slowly cycle between them both to enhance calf stretch.