To turn your PC on, all you need is the MAC (Physical address) address of the PC that you are turning on and Wake up on LAN or Power management from PCI enabled in the BIOS in the PC you want to turn on Remotely. To check if it is enabled or not, go to BIOS setting in your PC by restarting and pressing Delete key(may varry according to motherboard). Go to Power Management Options, search for Wake up on LAN or Power management from PCI or any similar terms and enable it.

If you don’t see any option to manage power for PCI adapters then it might be possible to do it in Windows mode.
To do this, boot your computer to windows, go to Device Manager. Under network adapter choose the Network card that will be used to connect to LAN, i.e. your ethernet card. Right click on it and choose properties. Go to Advanced tab. Now in Property box scroll down to Shutdown Wake up or any similar terms. Select it and Enable it.

You may require a reboot after this.
Now your PC is ready to be turned on from LAN. This will enable to manage power from PCI devices like Ethernet cards. What it actually does is, configures BIOS to turn the PCI Ethernet card to grab some power even if PC is Powered Off. If any computer from LAN sends some command to PCI card then will will power on your PC.
Now anyting left to do is to have a tool to turn your remote PC own from remote location. I often use this tool since its free and customizable. With this free tool you only need to enter IP address of your PC and it will automatically get the MAC address of it. If required you have password field to enter. Pressing Turn On button will turn on the PC with specified MAC address or IP address.

You can also check if the PC is on or off.