How do you get a 1999 VW Passat tire jack to open up?

I have just had my first experience with the jack for my 1999 Passat. It opens easily, just lay the base with the spring loaded pad on the ground and tur the handle in a clockwise direction. Then hope you can find where it is supposed to jack the car up from. the spots where the little plastic doors are seem like a likely place , Right ?? Well good luck. I tried 3 times to find a suitable spot twice the car fell off the jack while i was lifting . when i finally did get it up it started to roll backwards. luckily it stayed put long enough to get my floor jack under it !! Good luck with this piec of junk !!!