Log into Club Otto
When on club Otto home screen, click on the pic of all 5 cars.
From the list of cars, change qty of the car you want & click on book to add to your cart.
Click Confirm your booking, check your address & click next.

Cant really go any further as Im not ordering anything this month from Otto.

Just follow the on screen instruction / buttons. Then it tells you the postage cost. You then select what type of payment you want to do, card / paypal / bank transfer / pay later etc. Pay via paypal as normal.