Note that this page indicates that you must use Internet Explorer, and you must turn off popup blockers or put the site in your trusted sites list in IE. (The page is in .mspx format)
When you choose one of the 118 keyboard layouts, a popup appears showing the keys on the keyboard selected. If you hover your mouse pointer over the Shift key, and on some keyboards the Alt-Gr key, the shifted keys are displayed.
The popup window can't be resized, so you may have to use the zoom control at the bottom right to drop back to about 75% zoom to fit the whole keyboard in the popup window. The page cannot (so far as I've found) be saved for offsite reference. You may be able to save a "screen capture" (Alt-PrtScn) of the popup box, but I haven't tried it.
Windows contains a number of optional alternate keyboard layouts that you can choose to use, regardless of what physical keyboard you have. If you choose a layout that doesn't match the labels on your keys, I would expect some difficulties unless you are an exceedingly fluent touch-typist in the language chosen.