[Sabardeyn]

anitasimon1,
Windows 8 has two separate interfaces: Metro / Modern (the style was re-named but both terms are used) with the "tiles"; and, the Desktop - aka Windows as we've known it for the last decade but without a Start button/menu. I mention this because how you access Calibre depends on which interface you're using.

In Metro all you have to do is start typing "Calibre". You don't need to set your cursor anywhere. Metro will just assume you're trying to perform a search and show you anything with matching results as you type each letter.

Alternately, you can right click in any open space and at the bottom of the screen a menubar will appear. On the right, click All Apps and any software installed on your computer will be listed. (Click All Apps again to go back to the default Metro view.)

For the Desktop, click on the superscripted ">>" on the right, in the taskbar. That pops up a Start menu replacement, sort of. It works a bit differently but you can find most programs installed here. It's a bit odd from standard Start Menu since it uses folders (kind of like the Control Panel), but I cannot advise further because it depends on just how knowledgeable you are with where Windows kept certain features.

In case you don't have the >> (cannot recall if I tweaked something to get that to appear*), you can also see Desktop as the bottom left "tile" in the default Metro view.

To flip between Metro and Desktop, place your cursor in the upper left and/or lower left corner of your monitor, clicking on the one you want.

Oh, and Alt+F4 closes any currently running program. Period. The lack of window controls (minimize, close, etc) for most Metro programs drove me !! absolutely insane !! for the first week. I was frustrated, annoyed and ready to reformat my hard drive to remove Win8 before I learned that trick. I've been a computer "power-user" for decades but Win8 had me ready to chuck my CPU out the (house) window!

Sometimes when you start a program or click on a link you might get the Metro, instead of a Desktop, version of the program. The Win8 upgrade, called "Blue" or "8.1" (last I heard marketing hadn't decided on a name yet!) is due out now-ish and should allow you to customize things a bit - including starting and staying in Desktop among other things.

Oh, and right clicking and/or mousing into the corner/sides is a pretty common Win8 operating mechanism. It's Win8's version of "swiping" on a touch tablet.

*: Yes, it was something I tweaked. Right click on the taskbar in Desktop mode, then Toolbars>Desktop. It will add the Desktop toolbar (just those clickable ">>" to your taskbar).