How do I tell the special people in my life that I'm going away for a while to get the help that I need?

Just Tell Them. The "special people" in your life will be supportive of you getting the help you need and you cannot tell them in a wrong way. Try writing down what you want to say; find a quiet time and simply tell them what is on your heart.
Just like you did. There is no secret or magic in sharing difficult news with people, including people whom you care about. Sometimes its easier to call a family/friends meeting and tell everybody at once; other people do better doing it one at a time. The best way to do it is to do it. I understand that you may be shy and have problems communicating with others, but you can do it. Good luck in your efforts.