Red Field: Shoot the pokeball through the left outside loop. Each time you pass through the loop, one evolution arrow will light up. When all three arrows are lit up, shoot the ball into the Evolution cave. Then choose the pokemon you want to evolve.
For example, if you choose shellder, make the pokeball hit all three Water Stones then shoot the ball into the hole in the middle of the field.

Blue Field: Shoot the pokeball through the left loop. Each time the pokeball passes through the loop one evolution arrow will light up. When all three arrows are lit up shoot your ball into SLOWPOKE'S mouth. Then choose the pokemon you want to evolve.
For example, if you choose pikachu make the pokeball hit all three Thunder Stones then shoot the ball in the hole in the middle of the field.