Your goal is to plot two different columns, DSTV and VCC, on a Merged Y-Axis. See: Merge Variables on an Axis. Here's how it looks with the Big Class example dataset.

Clicking the line element will add it for both variables:

The final step is to disable the elements you don't want, as @jthi explained below. Continuing with my example for completeness:

If you want to try an LLM that is specifically trained on JMP learning materials, check out the LearnBot.