The new Metro UI of Windows 8 is pretty nice, but when it comes to shutting down or restarting the PC, its kind of hard because there is no visible start button which can get you the options you get in Windows 7, like Shutting Down your Computer or launching the installed application. Move the mouse to extreme right hand side of the bottom of screen to get the shut down, sleep and restart option. Here are keyboard shortcuts to perform certain action in Windows 8.
Press Windows Key + Q to Get the list of applications installed. Press Windows Key + F to search for Files on your Computer. Press Windows Key to switch between Metro UI and Desktop Mode. Press Alt + F4 to get the shut down, restart option. Here is a little tool that will create the start button in the Windows 8 and will also let you start your PC directly with Desktop mode by skipping the Metro Start screen. It functions like the start button in Windows 7 and will get you the list of install application and the search box to search app and files. You can shut down or restart the Computer by doing a right click on the start button, and you can also customize the actions of this start button by doing the right click on it. Download Start8 If Win8 feels little odd to you, try Classic Shell which also offers similar functionality.