How do you run the 800?

I'm in track and I'm running the 800 and mile. I'm afraid because I have never run the 800 before. I have been told to sprint the first 100, then stride, at the second 400 increase your speed then sprint last 200. Is this correct? I have been to one track meet and didn't do so well, have any tips? How can I conserve energy for the mile afterward?