How to find the mac address on windows.

 MAC (Media Access Control) Address is a unique address which is assigned to a network card by the manufacturers.

Mac address cannot be changed under the normal condition. It is the identity of the network or the user using that network. At some places it is illegal to change MAC address of any wifi card or any network card. 

Not any two network card will have same MAC address, it is a unique 12 digit no. Suppose if someone will do any thing miscreant from your MAC Address then you'll will be held responsible.

How to change the MAC address.

You can see your MAC Address by many means, one of those steps are:
Open the command prompt by typing cmd in the windows search from the start menu.
In the command prompt type "ipconfig /all"  Note that there is a space between g and slash(/).
After that the whole lot thing will appear on the command prompt.
In that list there is a 12 digit "physical address" That is your MAC Address.