My physiotherapy sheet makes sense in the clinic but not at home. What do I ask?

At home, the arrow on my exercise sheet seemed to point in two directions. I tried to remember what the physiotherapist had demonstrated and realised I had watched their hands instead of my own position.

The follow-up is in three weeks. My partner suggested finding a video with the same exercise name, but several videos use different starting positions. I have not tried to assemble a version from them.

I feel awkward contacting the clinic after confidently saying, "Yes, got it." The sessions cost £55, and I do not know whether a clarification would require another paid visit.

Would a message describing the exact point of confusion be enough, or should I ask to demonstrate it back to someone? The exercise has already been chosen for me. What I need to understand is the instruction I agreed I understood.