x11 for gimp?

hi, i’m trying to get gimp running for OSx 10.37 on my mac.
it tells me i need to have X11 to run this app.
there was a link bundled with the dmg, but it goes to a broken page.
does anyone know where i can get x11 to download?
also, can someone tell me in laymens’ terms what exactly it is and what it does?
sorry, i’m not a programmer, just an artist/ video director enthalled with the idea of moving entirely into a freeware workspace.
also if anyone knows of a freeware NLE for OSX, please post a link.
-i thought i saw in a thread about the orange project using blender as their NLE for the movie? is that right? how would that work?

nevermind, i stumbled across it at

but answers to my other question about an NLE for OS X that’s free would be cool…