It's not exactly like, but this sounds like it could be Diane Duane's 'So You Want to Be a Wizard'. That starts with a girl (Nina) who is being severely bullied. She finds a book called 'So You Want to Be a Wizard' and though that ends up becoming a wizard. She then meets a boy called Kit in a forest, who's had a similar experience. She has an affinity for natural magic and he has an affinity for technological magic. There's a dark wizard who is a running antagonist through the books and they end up in a world inhabited mostly by tweisted technology (like sentient cars).

It's the first of a whole series of books so if this is the one you remember then you have some fun reading ahead of you!