This can vary among different models. Most new eMachines desktops place it on the top of the front panel. There should also be a sticker on the back of the case right above the bus slots. On a laptop, look underneath, towards the the screen.
Model number, serial number and other information placed on the bottom of your notebook, if you have desktop this information placed on side of machine.
how does computer send data through serial port?
There isn't one. That model was made in 1963 to 1968. Serial numbers weren't required back then, and having a gun that never had a serial number IS legal.
It's a small programme that lists your PCs model number, serial number, model name and part number. It's handy if you ever need to contact customer support as they will ask for this info
what is the serial number of perfect uninstaller