Yes you can listen to your own heartbeat using a stethoscope.
All you need to do is put the stethoscope on your ears like the doctors do and then place the end of the stethoscope over where your heart is.
Your heart is more towards the left side but part of the heart is in the center of your chest and the heart is in the front and middle of your chest, behind and slightly to the left of your breastbone.
Part of the heart is on the left side of the chest but the middle part of the heart is in the center of the chest.