Actually, the instructions for adding media to SharedMedia are right in the SharedMedia folder that is in your "AddOns" folder. it's called "INSTRUCTIONS for MyMedia". It's a plain text file so you won't need anything extra to open and read it. It's a really simple way to keep your own additions to the SharedMedia addon when there is an update to it.
Just to make sure, here, we're talking about
SharedMedia by Elkano (and, apparently, a couple of other folks), right?