See if you can find your model here and refer to the instructions to see if you missed something when you threaded the machine - http://www.sewusa.com/Sewing_Machine_Threading_Diagrams.htm

Always thread a sewing machine with the presser foot up so the thread enters the tension so it will properly work when the foot is down for sewing.

Check the needle to be sure it is inserted correctly - this is usually with the flat side facing the back of the machine.

Hold onto the thread tail at the needle and handwalk the needle down and back up, which will bring up the bobbin thread.

Hold onto both threads and pull them under the presser foot and to the back of the machine.

Place the fabric under the presser foot. Lower the foot and move the needle down into the fabric - press the foot pedal.