The reference you're using is for Perl 4, so it's obsolete. Take a look at www.perldoc.org.

I'd suggest you install Perl locally if you haven't already. It comes with a wealth of documentation that is very easy to use. For example, if you want to find out what use does you can simply run perldoc -f use.

The use IO::File just loads the IO::File module. And then, yes, I'm instantiating it. I just wanted to show you that there's an OO interface available for file operations. And again, if you have Perl installed, you should be able to just type perldoc IO::File to read about it.