Do I need to turn off my thoughts?

Not at all. The last thing we want to do is create more internal struggle by having a fist fight with our own thinking processes. Instead, we gradually build our concentration power so that we can ignore thinking processes as we like and focus on whatever sensory experience we wish. It may be the case from time to time that thinking processes will quiet down or even vanish for a bit. That’s fine, but it is not the goal nor is it necessary to obtain all the benefits from meditation practice.