Could you explain how an increased temperature increases the rate of reaction?

A chemical reaction will only occur if the molecules collide with enough energy, when you apply heat to a reaction you're giving the molecules more energy so when they collide they're more likely to react.

Also, when molecules are heated they vibrate more. As there is more movement of the molecules they will collide more often. This means there will be more successful collisions and that means there is a faster rate of reaction.