How to add javascript to Simple:Press?

I’m trying to wrap my head around this, and just don’t get it. (Probably because I only know basic html/css, and WordPress is php heavy. Ugh)

Ok, so, I’m doing some work on my website. It’s a gaming website, and one of the things I’m adding is some javascript link syndication for game item tooltips for MMOs (Guild Wars)

I managed to get it to work via adding the jscript to the site’s header. If you go to this page and mouse over “Air Attunement”, you can see this script in effect. Ok, cool, works as expected.
http://www.rebirthgaming.org/development/

However, I’m primarily trying to implement this for our forum users, so they can use bbcode to add these ‘game item tooltips’ to their forum posts.
I use Simple:Press for our forums. I assumed that adding the jscript to the site template’s header would make it work for our forums, but it doesn’t.

BBCode works (which is how forum users will utilize this script’s feature), I can confirm that. However, look at this forum post, and mouse over “Air Attunement”. No popup tooltip. Sad face.
http://www.rebirthgaming.org/forum/guild-wars-2/test-post-disregard/#p72

I suspect I need to stick the jscript somewhere in the Simple:Press theme or plugin code, but no idea where.

Here is a reference for how exactly this script works.
http://www.gw2db.com/tooltips

Thanks in advance. This will be incredibly useful, because I have to do this for guild wars, WoW, and ESO item links lol!