the blue lines show you where you will end up and the yellow lines will move with the steering wheel.
so once the blue lines are where you want to be then straighten up and drive into your space,
an example would be reversing into a parking bay in a supermarket,you start reversing and get
the blue lines parallel to the white bay lines then you will be central in the bay straighten up and keep
reversing until the 1st line after the red line is at the back of the bay and STOP ,you will now have
enough room to get into the boot with your shopping.
i have an IS300h and have the flag system also ,this can be used to aid parallel parking between 2 cars
its complicated to explain just read the manual .