Recently, a friend of mine had to remind me that you don't have to tell the whole backstory in the first page or first chapter. You may feel like the reader will be confused if you don't or that they'll get bored if they don't know why every little thing is happening, but this is not true. In fact, the reader likes a little mystery, it's what keeps them reading.
When you begin a story, it needs to be attention grabbing, a hook that pulls the reader in and makes them want to continue reading. Something like, "My name is Casey and I'm fifteen," yada yada just wont cut it in the publishing world. Your very first paragraph, nay sentence, should have that special something that sets it apart from every other book out there.
Be sure that you don't tell the reader everything right away. Slowly reveal the plot, the characters personality and anything else. Keep the reader from getting bored and wanting to toss the book across the room. I am a very judgmental reader and if the story doesn't capture my attention or piles too much information on me right away, I hardly ever finish that book. It gets put in the 'started but never finished' pile and usually doesn't get pulled out.
There really nothing more I can say then read the beginning of your favorite book and determine why you kept reading it.
Happy Writing!
Kailyn