Wake on LAN is a utility to wake a device (PC, laptop, tablet) which is asleep and supports to be woken by Wake on LAN.
Add a configuration by specifying a unique name and mac address and select a picture (which will be used if a live tile is created). Multiple configurations for devices which can be woken can be created. For each configuration a live tile can be made.
Some simple explanation on WOL. Some devices support sleep/hibernate modes where the device (PC, etc) can be woken by a so-called magic packet on the ethernet (or wireless) interface. This tool can send this magic packet. To use the tool the mac address of the network card (or wireless adapter) has to be filled in (can often be found in routers). This tool will not work on internet, only on local networks. This tool only sends the magic packet. Putting a device in sleep where it can be woken has to be configured "manually". Most of the time it is a configuration setting in the network driver and it is called wake on magic packet or something similar. Sometimes it is required to configure the BIOS to support this. There is more information to be found on this subject on the internet.