How can i implement THREE.Curve to draw a 3D multiple vertex line?

suppose i have a line like the following image


i wanna draw this line from A to B to C
or C to B to A ,whatever,maybe 100 vertexs

it must extends the THREE.Curve class

I saw the Curve class but i dont understand , what should i do? any links or examples would be great

Compare this example TubeGeometryFrom2Dshape

from the Collection of examples from

It uses Curve.

Great!Thanks ROCK!