Demand curve confusion
The book probably intends you to think like this



so you have a downward-sloping demand curve (lower prices lead to higher demand), but if demand increases for a reason not related to price (a shift from the Demand 1 curve to the Demand 2 curve) then the new equilibrium on the upward-sloping supply curve will be at a higher price and quantity

There are a lot of implicit assumptions here, especially 


the direction of the slope of the supply curve
whatever changed the demand curve did not affect the supply curve