I would like to cancel my iPad order

Review your order status and options at this link:

Order Status - https://secure.store.apple.com/order/list

This link also has a lot of information about changing orders: Viewing & Changing Orders - Shopping Help - Apple

Your order confirmation should include details of whom you should contact in the event of a problem.

Contributors here are all end-users, just like you.

contact who you ordered it from?

Click on the second link I provided. It tells you all about changing orders.