It is common for first timers to be very uncomfortable with clipless pedals. Many struggle with clipping and most fall off within the first week of using them.
Here is a video like many others, a guy trying to use clipless pedals. However, something in me gets infuriated by this video. Maybe it's just me being OCD, but it really pisses me off. Lol
If you want to find out how to really use clipless pedals, check out this video: http://www.vingle.net/posts/446061-How-to-Use-Clipless-Pedals