I'm a new user of Linux/Ubuntu, and I'm still not comfortable with the notion of a packages. Actually, I'm trying to install Emacs 25.1 and I try to find out the good package in
emacs-25.1.tar.gz (see this website). Could anyone tell me what it is supposed to be?
If you want to build a package on your own, it is informative. I wrote it out: http://pj.freefaculty.org/blog/?p=328. The tarball you have is not sufficient to make a package, it lacks the "debian" directory that has the package building code. You might be able to compile emacs and install it, but it won't be a package.
Emacs25 has been discussed. I doubt it will build (discussed here Emacs toolbar icons missing in Ubuntu-16.10, struggle to compile emacs24 and 25), but conceptually it is not difficult: You run "./configure" (add some arguments), then "make" and "make install". Almost all GNU software is like that. I made some notes on compiling GNU stuff. Go here after slide 42 http://pj.freefaculty.org/guides/Computing-HOWTO/IntroTerminal-3/terminal-3.pdf).
As I said, I doubt Emacs25 will compile, you can't even compile Emacs24, or you could not when I made that post. If you try, you may need to install quite a few devel packages for your system. That's usual.
The shortest route will be "apt-get source emacs24". If you find a repo with emacs25, use instead. These will come with the debian subdirectory that guides the build.
Your question is a good novice question and I hope you'll keep trying. As put, you are asking a pretty giant question and that's why I'm pointing you at other locations to learn more. Try my notes.
A package is basically the data(the binaries, their icons, manuals etc) with some metadata which tells the OS where to put what(eg. put binary in /usr/bin, use xyz icon)
What you get on the website is basically source code. You can compile it, but you won't be able to create a package# unless
- You know which file should go where.
- This info is already provided.
get this info, and then you can build a package
A better option for a regular user is always to stick to the official repositories. If you don't find what you need there, look for unofficial repos. If you still don't find it, go for source code and just compile and install it. You don't(wouldn't/shouldn't) want to build a package unless you want to share it with others.
# source code might know how to install the software, but that won't be how debian/ubuntu expects it to be. The debian standard requires it in a specific format, which is adhered by the packages
I'm going to go on a limb here and assume that you don't care how Emacs is installed. In that case the easiest way is certainly the package manager.
Open the Software Center application, search for
emacsand install the package of the same name.
Alternatively you can open a terminal and run
sudo apt install emacs. This is also a good way to debug issues during the other approach (which often hides error messages or formats them disfiguringly).
Both approaches will install Emacs 24 (package
emacs24) in supported Ubuntu releases.