Don't know how to do CPR? The American Heart Association has some advice for you, in the form of this one minute video.
If an adult collapses, call 000 and begin chest compression -- don't wait or try to wonder how to do it correctly. Quick action can save a life.
The technique demonstrated is called "hands-only" CPR. If you want a rhythm to follow to do the chest compressions to, the AHA suggests the disco classic Stayin' Alive," which, as we've noted before, has approximately 100 beats per minute -- just right for how quickly you should compress.
Of course, this video is absolutely no substitute for taking a proper first aid class. CPR is one of the many basic life-saving skills everyone should know.