As far as telling your parents, there is not going to be an easy way, you will just have to sit them down and tell them that you are expecting a baby. They will be shocked and angry, but will more than likely support you in the end.
You need to call your doctor right away to set up an appointment, they will be able to monitor you and let you know how far along you are.
You should get on prenatal vitamins right away, you can buy them over the counter at a drugstore or Wal-Mart and a little extra folic acid is a good idea too (also available at the drugstore).
Try to get as much rest as you can, as early pregnancy is tiring.
Then you and your boyfriend need to begin making plans as to what you are going to do. Are you going to marry & keep the baby, are you going to stay unmarried and keep the baby, are you going to give the baby up for adoption. Are you going to try to go on to college or not.
You have lots on your plate to deal with right now, but you need to know that raising a baby is hard work and a thankless job. Ideally it is great to have a wonderful baby who relies on you for everything, but it is draining some days. My husband and I were married for 4 1/2 years before we had our son and it is a huge adjustment. I can only imagine that it will be more difficult for you.
You will need to prepare yourself for losing friends and not being able to go out. You will have to put your baby first and stay home with him/her.
You may want to consider signing up for parenting classes, check with your local non-profit agencies to see what they offer. If you are going to bottle feed, sign up with all of the formula companies (Enfamil, Nestle and others) for free samples and coupons. Sign up with diaper companies for coupons. You may even need to sign up with WIC (this will be later on, once you have had the baby).
I am not telling you all of this to scare you, I just think you need to know the road that you have chosen. You will be a mother for the rest of your life and this cannot be undone. With all of that being said, I wish you all of the best.