under 1, whilst holding baby on your arm, head pointing down, or across lap - up to five taps between shoulder blade (using fingers only)
if that doesn't work,
turn baby over, then up to 5 chest thrusts, 2 fingers between the nipples and push down about a 3rd of depth of baby's chest,
if that still doesn't work continue
Over 1,
child over lap or floor, 5 back slaps between shoulder blades,
if doesn't work
turn child over, up to 5 chest thrusts, one hand between nipples, again about 3rd depth.
if that doesn't work,
up to five abdominal thrust,
make a fist and place your other hand the first, make a scooping in and up motion, starting at the belly button. You're trying to force air up out of the lungs to propel the object.
NEVER to abdominal thrusts on a baby, and if you have performed them on your child, the child must go to hospital to be checked out.
HTH
(I used to teach it)