After your initial assesment you know more about the status of your patient and if they are not breathing you need to start Cadio Pulmonary Resuscitation (CPR) immediately.
CPR is not something you can learn from and article or a book or video. CPR is something that you MUST learn from a qualified instructor and do practically in training until you ‘get it’ 100%.
Do yourself and the people close to you a big favour and do a CPR course from a qualified instructor. Emergency Medical research continiously discover a better way of doing CPR and you have to do the course at least every 2 years to remain current and effective at saving a life.