install question

[Steven Arntson]

I've noticed that I don't have the most recent stable version of
Lilypond, and would like to install 2.18.2 to see if some issues I'm
having are resolved. The instructions on lilypond.org suggest installing
with:

sh lilypond-2.18.2-1.linux-64.sh

When I type this, though, I'm told,

You are about to install LilyPond in /home/steven/lilypond
A script in /home/steven/bin will be created as a shortcut.

These directories don't exist, and I don't really want to create them
just for one program. I'm the sole user of my machine, and I use the
Ubuntu package manager. I think Lilypond is in /usr/bin.

I'm new to installing things outside of Ubuntu's apt-get
function. (Alas, their repositories don't have very new versions of
Lilypond.) Is there a way to install Lilypond that will get rid of the
old version, and put the new one where it should be?

Thank you!
steven