Our dog, Amy, is old enough now her arthritis makes going up steps difficult, and jumping up into the car is impossible. I got her a ramp, but it is very steep up into the back seat of the TV, so we did the flat thing @Old-Biscuit describes to get her used to it. She is too old and afflicted to climb that steep ramp, but she will climb it as long as I stand next to her behind and "help." She's no longer afraid of it, it's just hard on her hips.
I agree carpeting the steps to block holes would be a good idea, if there are holes. Good luck.