To claim your tiles, click above, or just click a square. Click more squares, or hold the left button and drag to take in more: the rectangle around them fills in by itself. It works out the cost, and Add to My Ads Cart, top right of the panel, saves it to your cart.
If a postcode tile inside your ground is already taken, it is deducted. Otherwise it comes with your purchase: you cannot buy a banner tile without its postcode tile while that one is still available.
This is a demo ahead of the launch on Giving Tuesday, 1 December.