Avalon: Web of Magic Book 1, Circles in the Stream by Rachel Roberts
Three very different young teens, Emily, the shy one, Adriane, the outsider, and Kara, the power shopper, are all drawn to a secret place deep in the woods where they discover a portal to another world. Wondrous animals have emerged from the portal, desperately seeking the magic that will keep them alive. Though the animals are peaceful and good, what follows them through the portal is twisted and evil and bent on destroying them all.
The Fairimentals have chosen these three fourteen-year-olds to protect the magical animals. To save them and their world, the girls must overcome their differences and band together. They begin a perilous quest to discover Avalon, the lost, legendary home of magic, little knowing the terrible dangers they will face along the way.