Take a look at an easier and more effective method of CPR. This is a great video demonstration and explanation from the doctors who pioneered the procedure at the University of Arizona Sarver Heart Center.
This short video illustrates exactly what to do if someone near you collapses and is presumably having a heart attack. You could very well save the life of a friend or loved one by following these steps after 911 is called.
For every minute that CPR is delayed, the chances of survival drops by 10% so immediate and continuous action is paramount. Be a lifesaver; not a bystander.