You need to get a CD/DVD with the needed packages. This usually means that you go somewhere, where an Internet-connected PC is set up, and you download either a full IO or collect tons of applications packages (RPM, DEB or tarballs). You then burn it all to a CD/DVD and return home to your PC with all the treasures.
You then install the packages using the appropriate package manager, or simply unpack the tarballs.
To sum it all up: You need an Internet connection, though it doesn't have to be your own connection and not even at your own location. Some years ago Linux CD's where sold in bookshops or computershops, but these days, due to the Internet, those distribution channels became obsolete.