open a command prompt
run | cmd - ok
then either type
ipconfig /all
or
getmac
you'll see a series of number/letters
nx-nn-xx-xn-nn-nn
(in ipconfig it's called the physical address)
each physical network device (generally your network card or wifi dongle) has it's own unique address.
(it's a security thing .... don't give it out here ;o