Wake-On-LAN is a way to turn on you computer remotely. It can be in the same LAN or through the Internet.
To have Wake-On-Lan, your computer needs to support it. You can check your systems bios settings to see if you have the Wake On Lan option or not. If so, you just simply enable it and you are all set. Once enabl ed, log into the computer and copy down the on board NIC MAC address. You will need this MAC address when you want to remotely start up the computer.
Below is a Windows Wake On LAN GUI ultility that you can use:
Below is a Windows Wake On LAN Command file:
Wake On Lan from Wikipedia : With a more descriptive on how Wake On Lan works.