The open with option in Linux is similar to the open with option in Windoze. Select any text editor you have installed. I suspect Kubuntu's default text editor is Kate, but I don't really know. There may be several text editors installed to select from. Just poke around the menu and look for them. They are probably installed in /usr/bin if you need to enter a path.
Unless install-sh is in a directory that is in your $PATH, then you execute it thusly
Where the ./ indicates the directory you are currently "in." To see what is in your PATH variable execute in your console
However, it looks like you've downloaded the source code for Audacious. In that case you should install Audacious from the Kubuntu repositories rather than from source. If you insist on building from source, you'll need to do something such as
CC="gcc -m64" CXX="g++ -m64" ./configure --prefix=/usr --libdir=/usr/lib64 &&
make && sudo make install
Once again, however, you should use the Kubuntu repositories.
To see the manual page for chmod, which is more detailed than the help, try executing in your console