Need to convert a 2D line to 3D line.

Hi,
Everyone
I am new to the world of Qt. using qt4.5 with visual studio.
I have drawn a 2D line, and now trying to convert it in 3D(having Z- axis)
So please help me to design a 3D line .

Waiting for the answers..

Would you care to elaborate what you mean?

I mean that i have a line in 2D, i just want to make a line looks like 3D.

What do you mean that the line looks like 3D?