Right, and there's no standard for that. At all. Asking how to install a
tar.gz file is exactly as vague as asking how to install a Zip file. The
archive could contain anything.
That's why you have to read the README or INSTALL or similarly named file
that comes with the program. Most developers include such a file with any
source distribution telling you exactly what you need to do to compile,
including what dependencies you need beforehand. Again, there's no standard
for this, but since people distributing programs they wrote typically want
people to use it, they tend to do this.
If the documentation for compiling/installing/running a program is unclear or
missing, you should probably go to the developers of the program, or a
support forum or mailing list if the program has one.
As for the article about GNOME 3.14 stuff, Trisquel 7 includes GNOME 3.10,
not 3.14. But if you're only referring to GNOME Shell, you just need to
install the gnome-session and gnome-shell packages (in Synaptic), and then
"GNOME" becomes an option for a session type at the login screen.
