If you mean getting the thread from the bobbin part under the needle, this is how I do it (I have a Singer Stylist 367 machine, kind of oldish):
Make sure that the needle is threaded before you start...
There are 2 small narrow slots on the left of the bobbin holder - I put the thread out of the lower slot and back in through the upper slot. Then I pull the thread up near the needle foot, so it is coming out of the bobbin holder section. Next gently turn the wheel to lower the needle and to raise it it back up, when the needle comes back up it should have roped the thread from the bobbin and you should be able to pull it through from there.
Mags, June 2006