A "symlink", or symbolic link, is created using the
ln command with the -s (for symbolic) switch. There are several different ways of actually using the command, but I recommend
cd'ing to the directory where you want the link located, and then create the link with the command
ln -s <location we want to link to> .
The dot means "current directory", so the command above basically means "create a link named like the file or directory we're linking to in this directory".
So, for a real-world test:
cd to /usr/lib/mozilla/plugins, and if the plugin file is in /usr/local/java/j2sdk-1.4.2_03/jre/plugin/ns610-gcc32 then type
ln -s /usr/local/java/j2sdk-1.4.2_03/jre/plugin/ns610-gcc32 .
It's that simple. Make sure that you're linking to the correct file - I made up the location above so you may have better luck if you thoroughly research where the file is first.
Håkan