Hi there! Welcome to the site!
Well, the first thing to understand is that your parents are probably going to be upset... they may even want you to have an abortion. But they'll come around after a while.

(Even if it's not until they see your precious baby face-to-face) So you're going to have to be strong.
Ok, well, there are a couple of ways that you can use to tell your parents.
1. Just come right out and tell them. "Mom, I just found out that I'm pregnant" or showing them a pregnancy test can work.
2. Write them a letter. If they usually over-react to things at first, it might be a good idea to write them a letter and then leave for the day when they read it.
3. You could always say that you have something serious to discuss with them and ask them to take you out to a restaurant and then tell them during dinner (they can't freak out too much in a restaurant)
There are other ways, in fact if you look back in this forum on different pages you will see that there are a lot of ideas on how to tell your parents.
Make sure to let us know how it goes, ok?!