Sharing Minecraft with all users

Just switched to Ubuntu 14.04 from WinXP yesterday; so, I have much to lea. While I am, however, I'm trying to get Minecraft reinstalled for my son.
I followed the above steps and had no problem getting the game going - on MY account.
But, when I switched to his account to TRY the suggestions on creating a desktop icon launcher, Minecraft wasn't even available.
The jar file is in MY downloads folder but his folder is empty.
I certainly don't want 2 installations; so, is there a way to share it? Move it to a shared folder (I tried moving it to the Games folder but was told permission is denied)? Or, should I uninstall on my account and install on his?
I would really rather share it to all users.
Any help is appreciated; but, please keep in mind I have only a few hours experience with Ubuntu. I just don't want him to have to wait months while I lea the system.
Thanks!