Thread breaks when i start to sew

Question

i've followed the instructions several. i've even started all the way over & i still cannot get the sew mini to sew. when i try to bring the bobbin thread up, there is a lot tension on it & i can't pull it. once i finally do get it up & i try to sew, it will stitch a few times, then the thread will break. what am i doing wrong? how do i fix it?