Eye contact is extremely important in public speaking, and sometimes a challenge to master. It's one of the key ingredients that can lead to a very successful speech.
So how do you do it?
A trick that I always used in public speaking competitions when I was younger is say your entire speech to the back wall. This might seem a little silly, but it helps you master eye contact. Looking at the individuals in the audience, can make some people feel uncomfortable and more nervous than they were before. Also, actions from the audience (whispering, fidgeting, etc.) can become a major distraction and could make you even forget your train of thought. Looking at the back wall eliminates all these aspects from happening, and makes you feel more relaxed. If there is no back wall per say, pick an object that is the farthest away from where your staying, and still use this method that way.
It really is a clever tip, and can help you achieve eye contact in your speech.
