How to find your MAC address
The MAC (or media access control) address is a unique identifier for each one of your internet connections. You can have multiple MAC’s on your machine (for example, one for your wireless connection and one for wired). If you have more than one internet connection method, you will want to make sure to provide your wired MAC address, which can be found by the following ways.
On a Windows machine
Open the start menu and search for the command prompt by typing cmd into the search box, then click on the icon to launch the program.
(Note: in Windows XP, you will need to navigate from the start menu to all program->accessories->command prompt)
Once the program launches, type in the command ipconfig /all and a list of all your network connections will scroll. Find the entry titled Ethernet Adapter Local Area Network. The second entry under this heading will be called the physical address and be of the form XX-XX-XX-XX-XX-XX. This is your wired MAC address.
On an Apple Macintosh machine
Open up your system preferences and click the network button. Select your Ethernet connection and click the advanced button, then click the hardware tab on the new window to find your MAC address.
The prompt will stay up and the question will be added to your list. Continue to add up to three questions. Once you have finished, click the "close" button to close the security question window and then click the link for "Security Contacts" to continue.