I don't think telling him about .deb packages will help him any. Also, your link got truncated and isn't including the closing parenthesis.

In the top left of your device's screen, there is a button that (with the default theme) appears as either overlapping boxes (when you have an application open) or as six squares (when none are open.)

Touch that button until a grid of icons appear, then touch the "more..." icon in the lower right. If you have a lot of apps installed, you may have to scroll down a bit, but all installed applications should appear there.

I believe the "more..." icon is going away with the next update, so it'll be quicker to access the icons in the future.