Diesels work by compressing their fuel until it explodes. No spark is required to do this. But, with a very cold engine, just compressing the fuel & air doesn't work at all well. So, each cylinder gets a glow plug. It heats the cylinder a little just before you start the car.
Never having owned a diesel, let alone started one, you're going to have to ask the lady how to start it.
Be sure to ask her to have the car stone cold when you get there so that the time-to-start test can be fair. Preferrably, the car should be outside for a while, not in a warm heated garage. Of course, if you're in San Diego, this advice won't mean much. If you're in Chicago, perhaps the test is a wee bit unfair.