Horde3D

Hello, I am kind of programmer, and not a lawyer, could you explain me some examples where and how I can use Horde3d?

I am talking about this thing:


First of all, I am not that smart to make improvements to core, so I don't have anything to send back to community. Can I use Horde3d to build closed source commercial game?

If no, what's enough to do that? If I hire some cool developer and he make one or two changes in core and I send you this, this is enough for me to use Horde3D all my life? Or I must send you improvements all the time until my game released?
Not that I looking for wormholes, this is just kind of unclear.

Yes you can, but you should contribute back the changes you have made to the Horde3D if any.

ok, thank you. I will try to contribute something, but my knowledge at this things is not that high... in OpenGL especially