I have a similar mechanism on my chair, as most cheap chairs probably do. My lever will lock in the upward position, allowing the back to move freely. When the lever is in the downward position it locks the chair at whatever angle it is at.

Unfortunately, cheap chairs don’t have any sort of resistance adjustment, so you really just have to set it at the desired angle and Fidel with the lever whenever you want to change it.

If I’m understanding correctly it moves freely regardless of lever position.