When something good happens to you it is not surprising that you want to express yourself with joy. Feel free to say what caused the good thing for you and why it holds such a big meaning to you. The happier that you sound, the more believable your joy will be. Of course, you want to avoid sounding too obnoxious when talking about the good things that happened to you as it can make you seem self absorbed. So long as you are talking in a positive, non-obnoxious way, people will be happy for you.