On a tablet, you swipe it out from the left edge of the screen. Makes sense - so much sense that Apple copied the idea in iOS 7.
On a PC, you bring out the charms bar by frustratedly wiggling your mouse against the right edge of the screen for a few seconds before remembering that to make UI widgets appear out of the middle of the screen's edge, you inexplicably need to move the cursor all the way up or down to one of the corners.