Draw an Arc

I need to draw a curved line between two cubes.
I have found sth here :

but this is not clear to me.can sb please simply show me how to do this with a simple example ?
by the way, I am using Unity Pro 4.5.5f1 .
Thanks

Not sure you want an arc based on a circle or a Bezier curve… Assuming based on your own link, you want a Bezier curve…

Here is a page with loads of descriptions, but if you’re not into all the formula stuff, there’s load of free open source code too

Or, if you just want to mess with something first, here is a link to a package that you can import with example code and demo straight into Unity

(Scroll down to the bottom of the link for the package):
http://forum.unity3d.com/threads/bezier-curves-through-script.134810/#post-913528