If you need to boot a Lenovo Ideapad 100 from USB, there’s an easy way to do it.
First, shut down the computer. Plug a USB drive into one of the USB ports. Next, press the Novo Button. On my friend’s Ideapad 100 it’s a small recessed button between the power jack and the vent, toward the back of the machine. You have to press it with a paper clip. The Ideapad will start up and present you with a boot menu. Use the arrow keys to select the third option, which reads Boot Menu. Press the enter key. The computer will present you a series of options, likely the internal hard drive, the optical drive, or USB. Choose USB. The computer will boot off USB this time, then boot off the hard drive the next.
Getting any computer to boot off USB is almost always different from the next, but on this model of Lenovo, it’s pretty easy. You just have to know what that Novo button does.