For this stretch you start seated on the floor and fold your legs. You can sit on a block, folded blanket or a meditation pillow if you find you have a lot of tension in your lower back. If the legs dont want to sit folded comfortably dont force them, with time they should ease up if you stretch regularly. Keeping your back aligned, you fold forward. It's best to remain in the stretch for a few minutes and alternate the legs.
This stretch will specifically help with easing tension, is a good light stretch for lower back and glutes, and a hip opener!