Hold down the key on the left side of the keyboard, in between Ctrl + Alt, with the Windows logo on. Then whilst holding that down, press TAB. Each successive press on TAB will cycle through the windows.
Alternatively, instead of pressing TAB, roll the mouse wheel up/down. You can also use the mouse to point to the window you want. When you've chosen your desired window, let go of everything and it will come to the front.