The basic thing to remember when administering CPR is the ABC ( Airway, Breathing and Circulation) this was taught to me when i was still on college, when I entered the medics on our ROTC.
AIRWAYYou must first check that nothing is blocking your child's airways. Clear his mouth. Make sure there's no vomit blocking his air passages. Do a finger sweep of your child's mouth and nose to remove any block, position him on his lateral side so that if he vomits, it doesn't go back in his mouth.
BREATHING
Stretch the spine of your child and extend his neck so his body forms a horizontal line. If there is any kind of suspected spinal injury, don't move his body. Put your hand near your child's noce and mouth, and check if air is coming out. If no air is coming out, do CPR(cardiopulmonary resuscitation).
CIRCULATION
Make sure your child has a pulse. Check his neck or wrist. Observe the color of your child's lips and extremities. Raise his legs so that blood flows towards his chest.