Passing works like forcequake/mortar/equivalent skills: you activate the power (put it on your quickbar) and then paint a target on the ground. Click and it throws to the spot; ball goes to the receiver closest to the targeted area. Range is 30m I believe.
Yeah I'll note that when I started I wasn't aware of it, either.
It wasn't until I left the game and proceeded to quest and level up that I realized the game automatically adds the "Throw the Huttball" ability to next available quickslot.
Of course you can then move it to another slot and set a keybinding accordingly. A mouse button or whatever you want.
And the range is indeed 30m.