Are you using a thimble on the underneath hand? Some people use nails, as mentioned, or a teaspoon or some other kind of hard surface underneath.
The most common beginner mistake is to hoop the quilt too tight. Are you using a hoop? There should be a fist-size amount of "give" in the middle of the hoop. This allows you to manipulate the quilt sandwich onto the needle instead of just manipulating the needle. If you look closely at demonstrations of hand quilting, you will see that the quilt is being manipulated with the underneath hand at the same time that the needle is being manipulated.
Clear as much? Try loosening the sandwich and see what happens.