The View Options dialog box lets you decide which columns will be displayed in the main iTunes music library window. When you're looking at that window you'll see the items you have checked in View Options as a row of labels across the top, things like 'artist,' 'name' and 'album.'
If you click on any of those labels the whole library will be sorted by that category. If you click on 'artist', for instance, you'll get an alphabetical list of all your songs sorted by artist. If you click on that label again it will do a reverse alphabetical sort. If you don't like the order the labels are in, just drag them into different positions.