It's always rough when you are at an important function and don't know how to act. Here are a couple of tips:
1) Look the part. I had a manager who always told me to focus on the details of my appearance, it's true. If you look good and are well groomed you'll feel more confident.
2) Work on your social and conversational skills. You have to fit in to some degree, with your conversational topics and look. Keep it professional at all times.
3) Practice getting better, the more conferences you go to the better you'll feel.