Car Salary Sacrifice - Informing HMRC

[ianonline]

I am hoping someone can answer what I need to input in the boxes below informing the tax office via online I now have a salary sacrifice car "just add fuel scheme" through my work which myself/wife can drive, this is not a given company car for the job its a scheme where I have chosen a car for my own use
What value goes into "your contribution to price" I paid nothing up front for the car, just my monthly deductions
What do I enter in the Salary Sacrifice amount ?, is that my gross monthly deduction my company take from me prior to tax as set out in the agreement ?, do I annualise this figure ?
List price in accessories £27,500
Your contribution to the price ? (i didn't contribute so i assume this is nil)
Salary Sacrifice amount - Is this my monthly deduction prior to tax as stated in the agreement (£350) annualised so £4200
Your contribution to private use - Im guessing this is nil ?
Thanks in advance