Tap or click anywhere in the arena to move the food, or use the buttons. The highlighted cell leaves a full trail.
Wrong answers are fine here. Each one tells you why.
Your job
Drag a card onto a box, or tap a card and then tap the box's name. Cards are buttons, so Tab and Enter work too.
Drag the cards by their grip, or use the arrow buttons, to put them in order (top = first). Then press Check order.