Waking up the computer
The computer will appear to be off. You will need to press the power button, a mouse button (at least with an optical mouse; a mechanical mouse may work with a jiggle), or tap the keyboard to get the computer to turn on.
After waking, the computer will spin up the drives and the fans, and in under 10 seconds, you should see your desktop or the login screen, depending upon whether you chose for the computer to require a password upon waking. (The default setting is to require a password.)
If you are looking to wake the computer up remotely (for example, to connect to it via Remote Desktop), you will need to send a Magic Packet to the PC. The Magic Packet is a specially designed IP packet (usually a UDP datagram) that tells the NIC to wake the computer up. This Magic Packet needs the MAC address of the NIC, so be sure to have this information handy when configuring or using a Wake On LAN utility.
The easiest place to get this information is to click the Details button on the Network Connection Details screen shown above and look under Physical Address.