From a command prompt there's a sort of general-purpose file viewer program named "display". It will select a program appropriate to the type of file it sees and launch that program.
On the GUI desktop, the opening mechanism is very similar to how Windows works. Actually one of my biggest complaints about the Gnome desktop is, in fact, that it has slavishly tried to copy how Windows does it. Including some of the uglier bits.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.