Head south out of Snowbelle City along Route 20 and you'll enter the ominous Winding Woods. Upon entering the first area, you'll find a section covered in grass with a rock at the center. There you can level up Eevee and get Leafeon.
To get Glaceon first you'll need a Pokemon that can use surf. Go to Dendemille Town and then leave to the north to get on a path that leads to the Frost Cavern. Pass through the cave, heading upstairs through the doorway on the right. Make further progress and you'll eventually find a small stream. Next, use surf to reach the other side of the stream. Follow the path around and head downstairs. See that big glacier in the middle of the room? Well, that's an ice rock. Run around until your Max Repel wears off, then level-up an Eevee while near to the rock. It'll evolve into Glaceon upon completing a battle.